It was suggested in a comment — and I agree — that the previous open threads on the Fukushima Daiichi Nuclear Accident were becoming difficult to read, because they are such a mixture of technical details and philosophical discourse. That is, it’s generally a bad idea to cater to two different audiences in one comment thread. So, I will split them up.

Please restrict all discussion here to technical information, analysis, criticisms and questions on FD — no philosophising or excursions into whether nuclear power is ‘good’ or ‘bad’ or the implications of FD for the future of nuclear power (except for new technical developments, e.g. safety standards), etc. You may impart your deep wisdom on how the world should work on the other open thread I’m about to open.

Besides the above guidelines, the other rules of the Open Threads on BNC apply. Read here for details.

To kick off discussion, below is the latest FEPC status report (I’ll update this as new reports come in). You will also be interested in:

At 11:45PM (JST) on March 28, TEPCO announced that plutonium 238, 239 and 240 were detected in the soil sampled on March 21st and 22nd at five spots in Fukushima Daiichi Nuclear Power Station. Concentration of detected plutonium 238, 239 and 240 are the same level of the fallout observed in Japan at the atmospheric nuclear tests in the past and poses no major impact on human health.

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Latest from TEPCO Washington:
TEPCO Earthquake Information Update on March 28: Detection of Pu in the soil in Fukushima Daiichi NPS

On March 28th, TEPCO announced the result of analysis of plutonium contained in the soil collected on March 21st and 22nd at the 5 spots in Fukushima Daiichi Nuclear Power Station (See Map 1 bellow). As a result, plutonium 238, 239 and 240 were detected as shown in the Table.

– The density of detected plutonium is equivalent to the fallout observed in Japan when atmospheric nuclear tests were conducted in the past.

– We assume the current reactor accident was a possible cause of plutonium detected from two samples out of five ((1) and (5)), considering their activity ratio of the plutonium isotopes.

– The density of detected plutonium is equivalent to the density in the soil under normal environmental conditions and therefore poses no major impact on human health. TEPCO strengthens environment monitoring inside the station and surrounding areas.

– We will conduct analysis of the three additional soil samples.

We will continue the radionuclide analysis contained in the soil at three points in the site (See Map 2 bellow).

Result of Pu measurement in the soil in Fukushima Daiichi Nuclear Power Plant
(Unit: Bq/kg・dry soil)* :MEXT environmental radiation database; 1978-2008 Density of detected Pu-238, Pu-239 and Pu-240 are within the same level of the fallout observed in Japan after the atmospheric nuclear test in the past. Activity ratio of Pu-238 detected in site field and solid waste storage against Pu-239 and Pu-240 are 2.0 and 0.94 respectively. They exceed activity ratio of 0.026 which resulted from the atmospheric nuclear test in the past, thus those Pus are considered to come from the recent incident.

At this moment the source of the plutonium is not identified. Uranium fuel installed in each unit contains 0 to 1% of plutonium.

Since uranium fuel produces plutonium through nuclear fission, we can not determine that the detected plutonium is from the MOX fuel at unit 3.

The detected density is considered to be within the variation range of the density found in the ordinary domestic soil.

For reference, measured density of Pu 239 and 240 in the soil from Fukushima prefecture this year was ND～0.21Bq/kg from 4 towns surrounding plants and 0.61 Bq/kg from Fukushima City.

Detected density of plutonium is within the same level of density in the normal environment. Therefore there will be no direct negative impact on worker’s health.

The nuclide of plutonium is alpha. It can be shielded by a paper and does not penetrate skin. Therefore, the effect of external exposure on human health will be negligible. However, if it is orally ingested, it poses risk of internal exposure. If we suppose oral intake of 1kg of sample soil which includes highest concentration of plutonium 239 measured this time, which equals 1.32Bq/kg・drysoil, the internal exposure is approximately 0.3 microSv. (1.32 x 2.5 x 10 E -4 = 0.00033 mSv = 0.3 microSv)

– Based on the evaluation method by the Japan Society Civil Engineers, we voluntarily conducted an assessment regarding Tsunami of O.P. 5.1～5.7m.

– However, we haven’t anticipated an earthquake involving all regions from offshore Miyagi to Ibaraki simultaneously.

– The Headquarters for Earthquake Research Promotion is stating that “an earthquake involving all regions from offshore Miyagi to Ibaraki simultaneously” was beyond consideration.

– We acknowledge that at the joint working group for earthquake resistant engineering, there was a study to take account of Tsunami by Jogan earthquake and there were reports and presentations published.

– However, we understood that the study was not completed as a unified opinion and required further research. Even so, we paid attention to the study and from last year, we voluntarily began to conduct the investigation on the Tsunami sediments and publicized the results as a thesis.

– The magnitude of Tohoku- Pacific Ocean Earthquake by far exceeded that of Jogan earthquake of which there are various estimations regarding the scale.

– When TEPCO applied for the site permit of Fukushima Daiichi Nuclear Power Station, we assumed O.P. + 3.1m as the highest tide level taking Chili Earthquake in 1960 into consideration.

– Since the Tsunami analysis techniques have been developed, based on the evaluation by the Japan Society Civil Engineers, we predicted O.P + 5.4 to 5.7m assuming various earthquakes off the coasts of such as Sanriku and Fukushima (Keicho earthquake in 1611 was also taken into account). Based on this evaluation, we took safety measures such as elevating motors for pumping up seawater used for back-up diesel generators.

– The headquarters for Earthquake Research Promotion is stating that they had evaluated seismic motion and Tsunami in each specific area, and that however an earthquake involving all those regions simultaneously was beyond the scope of the assumption.

* Barry, you calculate a dose for Pu-239 ingestion, but I believe Pu-238 is the most radiotoxic. Not that it matters much — the focus on plutonium is hugely overhyped. But it would be nice to see some calculations — I suspect the in-core radiotoxicity of Cs-137 alone exceeds all Pu isotopes.

I’ve found some dose factors here, but need to track down more of them:

* The dose rate in #2 turbine hall basement is reported as “>1,000 mSv/hr” (exceeded measurement limits); based on the activities reported below, it could be much higher. Fission product concentrations are between 25-60x higher in #2 turbine hall standing water than in #3, where the surface dose rate is 750 mSv/hr. (It’s been reported that the I-134 measurement is an error). Of course the amounts and geometry also matter.

* I’ve made comments, on my blog, about the measurements of I-131 and Cs-137 fallout in (unevacuated) parts of Fukushima prefecture, e.g. Iitate. Cs-137 deposition has been inferred in the range of 3 – 8 MBq/m^2. How should this be interpreted?

Being very familiar with the designs of modern plant that would be built today (contrasting the out of date Fukushima plant), I would like to add my analysis of why I believe an accident of this magnitude could not occur in a modern reactor such as the EPR or AP1000:

Most importantly, the back-up power systems could not be simply washed away by a tsunami as they were at Fukushima –

In the EPR design, there are four separate ‘redundant’ diesel generating systems, two of which are bunkered and waterproofed, each capable of keeping the core within safe temperatures following shutdown. If built near the coast, the diesels could be placed on the side of the containment furthest away from the sea, and so use it as a further barrier to extreme weather, such as tsunami.

In the AP1000, all the safety back-ups are protected within the containment and exterior shield building, and so would not be at risk from even the most extreme weather anomalies. The safety systems do not require fuel, as they are designed to allow water to simply fall into the core under gravity and circulate via natural convection etc.

Even if all these safety systems failed and there was fuel melt, the external radiological consequences would still not be as high as even the relatively minor release experienced at Fukushima. Firstly, both plants have hydrogen mitigation systems, so no scary explosions. Further, the EPR has a double layer containment and corium spreading pit (nothing is getting out of there) and the AP1000’s steel containment can be cooled from outside almost indefinitely.

Long story short, the main technical lesson to be learned from Fukushima is: Build new reactors!

On topic — what these threads really need is a YCombinator-style tree hierarchy for comments. It would be much easier to follow discussions of the size this blog gets.MODERATOR
See Barry’s remarks at 11:16 am

For the Fukushima reactors, does anyone happen to know, or perhaps have resources where you could find out:

1) just where the dry well containment atmospheric monitoring system radiation monitors are located?
***I’m wondering if they are external to the dry well (e.g., still reading air) or
***if they are actually in the dry well, in which case, they’d be under water now since they’ve been flooding containment, right?

2) just what type of monitors they’re actually using?

3) what is the normal range for those rad monitors
***under operating conditions, and
***post shut down (1 to 30 days, but I’ll take any data!)

well, this sounds pretty wild (see below). Note that even tho the wording would lead one to assume that options in the second paragraph are being considered by the experts, what it REALLY says is that the media has said those things. So, maybe the experts have discussed those, maybe they haven’t, who knows.

…Chief Cabinet Secretary Yukio Edano told a news conference that the government and nuclear experts are discussing ”every possibility” to bring the plant under control and that some measures that have been reported by the media are included in their options.

Media reports said that the government and the experts have been studying the feasibility of new steps such as covering reactors of the plant with special cloth to reduce the amount of radioactive particles flying away from the facility and using a big tanker to collect the contaminated water….

Barry,
I think you mis-posted this comment:
“Please keep all dialogue here to general and philosophical discussions on nuclear power, its benefits and limitations, its alternatives, history, media treatment of the FD accident, your views on how the world should work and why people should listen to you, etc., etc. Nothing technical please — leave that for the other FD open thread. […]”

Rational Debate,
Dry monitors are usually super sensitive, capable of reading well below background and installed in specially shielded boxes (we use boxes made of lead that was smelted more than 2,000 years ago).

Thus we can measure tiny amounts of radioactivity in air but usually it is unimportant owing to the very short lifetime of the radioactive isotopes of Oxygen and Nitrogen.

Wet wells are something else as we are looking at ground water that will likely contain sodium and chlorine. Personally I don’t take much notice of Chlorine but sodium can present some problems with its many active isotopes.

Live NHK TV reports that some people are filtering back into the 20km area to check on livestock, and property. Of course, they’re not supposed to. It’ll complicate any dose estimates if much of this happens, but I suppose the only surprising aspect is clearly some aren’t that scared of the radiation.

Apparently they are thinking that some/much of the trench water is from the tsunami (seems likely to me). The entire area has got to be pretty saturated from the tsunami. I am sorry that I don’t recall for sure where I heard or read this – I think NHK live TV but I’m not certain.

NHK live TV reporting that at Ofunato (sp??), near Sundaii (sp??) is so far the highest spot where the tsunami came in. Apparently there the tsunami reached the top of a cliff (hill?) that was 29.6 meters high. Which I just HAVE to put into feet, for those of us who don’t think in meters – the blasted thing was over 97 feet high!!!! I’m sure it had to have been like the video that Barry posted on another thread – not some giant breaking/crashing wave coming on like a 97 foot high wall, but just the water rising and rising and rising…. ah, here’s a link & story (below). There is a video at the site too.

They’re also reporting supercritical flow at another site – I didn’t catch exactly what the mechanism is, but apparently the result is water moving overland at extreme velocities. One woman was quoted as saying the water was moving almost as fast as the bullet train. Here’s an article that talks about one mechanism (maybe the ony one? I don’t know), http://nctr.pmel.noaa.gov/titov97.html scroll down to the colored mockup, and read the paragraph below. It notes speeds up to 40+ mph (19 m/s) in one known case. I couldn’t find a link on NHK with the details that they were reporting on the live TV.

We’ve discussed this on other threads. I haven’t read your link, but I wouldn’t think Te-129 would be a big surprise. Hopefully this will work, I’ve never tired copying a comment link from the date…. but try this and see if it doesn’t get you to one of our earlier discussions where you can see what has been said about Te-129 previously and then we can talk about it more here if you have more questions/commments:

Ok, it’s going to be wild if they tent the reactor’s to ‘catch’ radioactive particles! Apparently that really is under consideration. I’m not sure what they’d do that way – but suspect it would be a first. Wonder what sort of ‘cloth’ they’re considering…

Japan is to decommission four stricken reactors at the quake-hit Fukushima nuclear plant, the operator says.’

What do they mean?! I did not think they would be using them again. What are the implications. How does it change the way they do things? (What is this message meant to mean. Is it code for something?)

One of my friends in a different forum (who has been a bit on the hysterical side throughout all this) reposted a news item reporting a fellow named Richard Lahey (a General Electric identity,allegedly head of reactor safety) suggesting that in his opinion, the readings suggested that the reactor core had melted through containment.

This seemed at best fishy to me (especially since it hadn’t been mentioned in other news sources), so I wanted to get some idea where this had come from. Does anyone know?

Comes from Arms Control Wonk blog. And you’ll notice Red_Blue has already had his/her say in the comments.

El, the author launches into all sorts of calculations without first looking at the big picture. If there were Cl activation, there would also be significant Na activation. No activated sodium was found apparently. Other short lived fission products that would be expected to be found in significant quantities weren’t either. That puts a rather large hole into the scenarios proposed in that paper, or in the idea of Cl-38 arising from a re-criticality.

I’ll cross post this over on the technical open thread where it would make more sense for us to continue discussions on this issue if desired.

TEPCO’s March 29 assertions mentioned by Barry at 11.45 am should be considered together with this reuters report claiming that they in 2007 they had an internal study estimating a 10% probability of a bigger Tsunami than design basis within 50 years but did nothing about it.

@Huw Jones, on 30 March 2011 at 12:28 PM said:
“… an accident of this magnitude could not occur in a modern reactor such as the EPR or AP1000”

Apart from the over-confident “could not occur” I accept that the AP1000 is much safer, but several questions and issues remain:
.1 the fact that the US began many of these design alterations as early as 1972 shows that the stronger regulation in the US and Europe is totally justified. I raise this because both BB and many pro-nuclear advocates have complained that regulation in the west is too zealous and unnecessarily increases the cost and time of construction.
.2 Given that the Fukushima type reactor and its descendants are the most common type, how many of the >400 extant reactors meet the higher standards discussed by HJ? Especially outside the US. Generally speaking I would be in admiration of Chinese engineering projects, however the huge cost of these things and the huge demand on concrete and steel makes one nervous, not so much about the government, but about the contractors building them to cut corners. Even in Japan there were dark stories about contractors bulking up with straw, some of the concrete structures that collapsed in the Kobe earthquake.
.3 re: “could not occur”. The weakness in the Japanese design was that all the backup systems failed because they all relied upon the same electrical control room, switching room and pump room (which to this day, despite restitution of mains power remain unrepaired). Except for their Pacific coast, tsunamis are not the rogue issue for the US but apparently many experts claim that there is an equivalent risk in fire, which is a common occurrence from earthquakes (many examples must have been documented on the BNC site; it was true with the 2007 Chūetsu offshore earthquake that shutdown all the Kashiwazaki-Kariwa reactors.)
I pointed out this flaw in my Crikey summary of 16 March, and so unlike most commentators was not surprised that the mere reconnection of mains power has still not restored normal cooling, absolutely critical to stop things getting worse.http://blogs.crikey.com.au/rooted/2011/03/16/japans-nuclear-crisis-the-technical-facts/
Below is a fuller explanation of this weakness. (This is my selection/extract from the much longer article.)

The primary challenge for the Japanese reactors apparently resulted from losing both their normal and back-up power supplies. The reactors were designed to cope with this situation for only eight hours, assuming that normal or back-up power would be restored within that time.
……..
Most U.S. reactors are designed to cope with power outages lasting only four hours.
……..
We know that earthquakes can cause fires at nuclear reactors, and U.S. reactor safety studies conclude that fire can be a dominant risk for reactor core damage by disabling primary and back-up emergency systems. Yet dozens of nuclear reactors in the U.S. have operated for years in violation of federal fire protection regulations with no plans to address these safety risks anytime soon.
…….
Finally, there is the issue of protecting nearby communities. The breadth of the disaster in Japan overwhelmed emergency response capabilities. Reactor emergency plans in the U.S. rely on the assumption that a reactor accident would be the only demand on emergency response resources.
——————————————————-x

Hi RD
In my opinion the Te-129 issue is quite very surprising.
The Te-129 measurements in the air are quite erratic and if they’re not another measurement errors they would strongly suggest massive concentration change UP very recently between 3/23 and 3/24 because the Te-129 value jumps from order E-3 to E-0, also the Te-129/Te129m ratio changes massively throughout the later measurements which could be due to different half-lifes, but the ratios don’t match and Te-129, which has much shorter half-life than Te-129m looks like it sharply rises its ratio to Te-129m
What could it mean?

to admins:
to limit the amount of links in a post is pretty nonsense, this is a technical debate, so to provide links to multiple sources is important. like this you must unfortunately find it for yourself from Tepco measurements.MODERATOR
I am not quite sure as to what you are alluding. Refs/Links are actually encouraged by BNC. Too many links in a comment, however, do sometimes mean that the comment may be deemed spam by WordPress. I will pass this on to Barry for comment.

One of my friends in a different forum (who has been a bit on the hysterical side throughout all this) reposted a news item reporting a fellow named Richard Lahey (a General Electric identity,allegedly head of reactor safety) suggesting that in his opinion, the readings suggested that the reactor core had melted through containment.

This seemed at best fishy to me (especially since it hadn’t been mentioned in other news sources), so I wanted to get some idea where this had come from. Does anyone know?

This is reported in the Guardian, a perfectly credible British newspaper:

Richard Lahey, who was head of safety research for boiling-water reactors at General Electric when the company installed the units at Fukushima, told the Guardian workers at the site appeared to have “lost the race” to save the reactor, but said there was no danger of a Chernobyl-style catastrophe.

[…]

At least part of the molten core, which includes melted fuel rods and zirconium alloy cladding, seemed to have sunk through the steel “lower head” of the pressure vessel around reactor two, Lahey said.

“The indications we have, from the reactor to radiation readings and the materials they are seeing, suggest that the core has melted through the bottom of the pressure vessel in unit two, and at least some of it is down on the floor of the drywell,” Lahey said. “I hope I am wrong, but that is certainly what the evidence is pointing towards.”

Just heard on NHK that the other Fukushima plant Dai-ni has been observed having smoke coming out of one of the turbine buildings. It has stopped, but I want to know if this is also in trouble. Why do they observe the smoke but not know why. Feels a bit like they are not in control.

Rational Debate,
To clarify my earlier comment I was talking about what we do in North Carolina so things may be slightly different in Fukushima.

Most of our area monitors have local displays which can be read from at least 50 feet away. While the instruments can read down to background, anything below 1 milli=Rem /hour displays as “Zero”. Depending on location these monitors are set to alarm at a few milli-Rems/hour.

The really sensitive instruments are used in the air quality monitors in the very high radiation areas where there can be measurable activation of the air. These monitors are inside specially shielded boxes made of ancient lead to ensure that they are not affected by anything but the air circulated through the box.

Several comments have suggested that keeping one of the power plants in service (or hastily returning it to service) could have solved the power problems which were due to the tsunami taking out all 13 diesel power plants at Fukushima Daiichi.

Not so.

See my post on the philosophical thread, several minutes ago for a more detailed discussion.

The problem was and is, to this day, that the various control rooms were flooded and could/still cannot be reconnected to power. One week after mains power restoration they still haven’t been reconnected (except for lighting!). Mains power would have been more convenient because they did have trouble with provisioning diesel–actually running out at different times. Indeed this loss of normal cooling circuits has been THE central issue which has forced them to use firetrucks to pump in seawater.

Fair enough. We tend to agree regarding power, although coming at the issue from different directions.

Regarding Crikey, I have tended to spend more time on BNC lately and less on the Crikey that I pay real after-tax money for. Living in NSW as I do, the political stuff has been a bit over the top lately and the rest, well, is less relevant to the real world than that which is happening in Japan and its possible effects on our futures.

Incidentally this issue (slow re-installation of control rooms etc) and today’s report of steam from one reactor at Dai-ni, raises again to me a mystery. Why did Dai-ni escape apparently scot free? Apparently the tsunami was just as high there. So did the design of the plant provide more protection (bunkered & waterproofed)? I have never seen anything written anywhere that comments on this huge difference. Dai-ni reactors were built a decade later so one could infer (as much as I hate getting into a speculative loop like so many comments on this site) that the Japanese/TEPCO knows perfectly well how to build properly protected plant and just kept running the old ones hoping for the best. (Just in February they won a 10 year extended life for Dai-ichi #1, the oldest one.)
Note also that Dai-ichi #5 #6 have had no problems (apparently, despite outside experts worrying about them) but are only a few years younger than the others at Dai-ichi, but you can see these two are physically separate to the others. They had fuel in the SFP storage (and #6 had the most because it is the only 1.1GW reactor on the site).

JB, I didn’t claim I wrote about what you did today. I said that what you wrote about was beside the point (well, I wasn’t so blunt in my first post but that was it).
Just in case it is still unclear: even if one of the NPPs could have kept running, it would have made no difference (other than a bit more convenient–avoiding diesel issues).

MRJ:
Sorry not to provide a link. I read somewhere today that the newer power station is actually quite a bit higher than the older one.

I guess that, being a decade newer, might also have made a difference in terms of watertightness of switchboards, building layout (shielding from the tsunami) or many other small hypothetical ways.

Without a site plan and witness reports, however, this will remain just conjecture.

Time will tell. Surely, there has been enough bad luck already?

BTW, I notice that you, like me, have confused the names of the two power stations. Fukushima A and Fukushima B sound good enough for me, akin to Loy Yang A and Loy Yang B or the former alphabet stations at Vales Point and Wallerawang in NSW.

Hello everyone. I am interested in the rough cost of possible upgrades to existing older plants, such as
– very tall tsunami walls
– full passive steam powered pumps and valves
– much more battery capacity (say 10x more?)
– very large eathquake and tsunami proof demineralized water supply tanks next to the plants
– etc,

What would be the cheapest combination of upgrades to get some serious tsunami protection for Japan coastal plants?

Putting waste water from the flooded turbine room into the condenser seems like a bad place to put it as it communicates w/ the sea water used to cool the condenser. I heard earlier it was not the condenser but the condenser TANK. Can anyone add some details??

here there is a very interesting interactive map of all the Geiger meters of Japan, each one has the location, the average reading* and the organization managing it.
very useful for a general look of the network, for historical reference. hoping to be useful

“this will remain just conjecture.”
Quite but why would it not be worthy of mention? (It is the nitpicky scientist in me. I want to know.)

“BTW, I notice that you, like me, have confused the names of the two power stations. Fukushima A and Fukushima B sound good enough for me, akin to Loy Yang A and Loy Yang B or the former alphabet stations at Vales Point and Wallerawang in NSW.”

Hmm. Trying to figure what you mean. It’s near midnight so could easily makes error but I checked what I wrote and I don’t think I got anything mixed up. Fukushima-I = “Dai-ichi” with 4 of 6 reactors in trouble, while Fukushima-II = “Dai-ni” with 4 reactors in cold shutdown.
——————————x
@Cyril R.
Read Huw Jones, on 30 March 2011 at 12:28 PM about the American regulators changes to the design of these things (in the AP1000). You’ve really got to protect the control room and all important mechanicals (pumps etc). Probably making battery installation that big might be more trouble than it is worth; I am wondering how the batteries survived the tsunami when everything else didn’t.

Re battery rooms, it is common practice in coal fired stations to locate the battery rooms very close to the control rooms, to ensure max possible security of DC backup for control systems. Plant control rooms tend to be a bit elevated because the operating floors are at turbine level. The same kind of reasoning might have placed the batteries above the worst of the tsunami. Again, only conjecture until actual layout drawings come to light, but certainly plausible.

For new designs yes this is easy with passive features but what about existing ones, especially older ones on the Japan coast?

Batteries can be made very robust and water resistant. If they are just for some valve actuation and some critical DC controls, they are not very high power systems, and maybe several days of deep cycle lead acid won’t be all that expensive? Couple million more in batteries isn’t going to break the bank. Or there could be a separate diesel generator to charge the batteries up so that they can last a couple weeks?

It seems to me that some quite cheap upgrades can be done to the older plants to make the Fukushima proof. Closing them down means more fossil fuels that kill people all the time, pollute the air a lot and could cause possible severe climate events.

It’s a common industry practice(at least according to NRC documents I have read) to offload all the fuel during refueling, then replace about 1/3rd of it then load that back into the core.

So it was a ‘worst possible time’ at reactor #4 to lose power to the spent fuel pool. It had a full hot core sitting in it. Number of fuel assemblies in a pool is part of the story. How long they’ve been there is just as important.

I posted the question on the 3/26 thread with no response but that is probably because everyone moved over here “overnight” (for me ;-)

so the French appear to want to come help “dispose” of the radioactive water.

dumb question: does this mean burying it in a tank somewhere for x number of years, or did I read correctly that there is technology that exists that can “clean” (filter? forgive my layman’s terms) the water so it is not so “dangerous?

NHK’s statements implied a way to rectify the situation with the contaminated water instead of simple disposal….

@GSB 12:05 AM The following is my opinion based on large steam turbines in the process industry, not nuclear power plants. The basic principles are the same.

Turbine steam condensers are horizontal heat exchangers with the steam on the shell side, condensing on many rows of horizontal tubes which have pumped cold seawater flowing inside them.

The condenser heat exchangers drain the condensed steam into (horizontal) large pressure vessels. These vessels may operate 50-60% full and act as surge volume in the system. They operate at ~atmospheric pressure, +/- alittle bit. The surge vessels may be separate from the condenser or be built in one large common shell with the condenser tubes above the water surge volume.

Below the condensed steam surge vessel are the primary circulation pumps. The are located below the vessel so they have a head of water for the pumps to work properly (net positive suction head).

There are probably secondary circulation pumps to boost the reirculated water up to ~1000 psig which is the operating RPV pressure.

Depending on the condenser surge vessels size and the amount of water in them post shutdown, there may be room for some additional contaminated water in them, if a way of pumping into them could be found.

Thx for the response Leo that makes sense– the condensate tanks more than likely would be isolated from the sea water side of the heat exchanger.

I conjecture that there might me one or more breaks in the primary steam turbine loop from the earthquake….on this BWR design there is only one loop so radioactive water left in the loop could leak out in any number of places and it is my guess that perhaps this is where the water in the turbine room has come from (pure specualtion).

Question:
If there are breaks in the primary turbine loop how does this inhibit getting the cooling pumps going again??? Is the cooling loop they are trying to get started part of the primary loop or is it a second, smaller and simpler loop that could be used independently from the primary loop.

Folks: I posted on the philosophical thread a scary story about the effects of a meltdown along with a much less scary story from the guardian. The titles appear to be antithetical. I should have posted here.

FYI,
I have a friend in the GE power division and he says TEPCO just placed an order for 40 new 9F gas turbines to replace the load. (10 GW total output). To be fueled on DF2. Not known is if they will be combined cycle units.

I’m not ignoring your question, just have to get time to take a closer look at the data & ratios. If you feel like pulling the actual number out and posting them that would help. I’ll try to take a look later today.

Is it just me, or are those levels unsurprising/underwhelming? …Pu-238 decays.

Nope, Maud, it’s not just you. That’s a huge problem for the industry wrt both regulatory limits and even more, public opinion/understanding, especially in crises like this, as rare as they occur. We can measure radioactivity down to such utterly minute levels, yet we are tied to ALARA (As Low As Reasonably Achievable) in terms of both occupational and public doses – and yet anytime any radiation is measured, many in the public get worried because ‘that must be bad, right?’

Anyhow, in answering your question I’m forced to bring up issues that are probably better suited to the philosophical thread, but I was trying to answer your question – e.g., ya, those plutonium measurements so far are extremely low, you are exactly right.

George, I’m not a system’s engineer, but I can’t imagine that they’d be trying to start up anything associated with the primary turbine loop. There are a few different cooling loops that they may be trying to restart – residual heat removal (RHR) the most likely one I’d think – but it would all depend on just what pumps or electrical circuits, etc., are damaged, and how easily or fast they can repair or work around what ever problems they find.

Thanks Gallopingcamel. Here’s what I’m trying to get at. The Fukushima data is showing massively high dose rates in their dry well CAMS. I’m trying to figure out just what the significance of that is in terms of plant/core/RPV condition – but I’m not certain of a couple of key aspects:

Where those would actually be placed – I mean, they’ve been flooding the drywell, right? So if the CAMS are inside the drywell, they’d be underwater. ***If that’s the case, any idea what that would do to readings?

Huh, just occurred to me – I wonder if the placement is such that it might have gotten hot enough to melt the lead (327.5 C)? If we lost the lead shielding, any idea what sort of dose rate they be likely to see from shine, assuming no core damage?

Shoot, GallopingCamel, any thoughts one way or the other about the screamin’ CAM readings? It’s at all three units, although there is some variation. I can find you a link if you haven’t seen the data, its one of the pdf type reports, so I think it’s either nisa or jaic, maybe the latter…

Plutonium stays in the body when ingested or stuck in the lung. It then goes and radiolyses your body cells and water from within, nasty.

However, different isotopes of plutonium have huge differences in biotoxicity. Pu-238 is very dangerous when ingested, possibly over half of it will decay in your body, Pu-244 really not so much because it is very long lived, very slooooow decaying, a fraction of a fraction of a fraction will decay in your body. If the contest would be to eat pure caffeine or Pu-244 I’d take the Pu-244, but contests like that are silly sensationalism if you ask me, though Cohen’s point was made quite clear…

Most Pu from the reactor will be Pu239 and Pu240, both also orders of magnitude less dangerous than Pu238.

Some posters in previous threads on this site seemed to discount the report that reactor unit 2 appears to have melted down through the bottom of the containment vessel (source: http://www.guardian.co.uk/world/2011/mar/29/japan-lost-race-save-nuclear-reactor?intcmp=239). Those posters stated that the steel of the primary containment vessel was too thick to melt through, even with fuel rods being partially exposed for weeks and temperatures in the reactors exceeding design criteria. However, there are other factors that may have caused the reactors to lose containment.

Is it possible that the spraying of cold water on the hot pressure vesselsl could have opened cracks in these old reactors, weakened from decades of embrittlement? Could embrittlement have weakend the pressure vessels enough to have caused them to lose containment due to the stress caused by these changing temperatures?

Also, “in 2002, an undetected boric acid leak at the Davis-Besse nuclear power plant in Ohio ate through most of the 6-inch-thick steel reactor head. When the leak was discovered, only 3/8 inch remained.” (source: http://newamericamedia.org/2011/03/us-takes-second-look-at-nuclear-safety.php). Is it possible that chemical reactions with the boron or impurities in the seawater could cause something similiar to occur in these reactor vessels?

i am looking for radiation measurements on land from 1-10 km from the power plant. Anybody know any good sites (I find lots inside the gates and >20 km, and a few marine measurements, but none on the ground). Thanks.

Apologies if this has already been posted elsewhere, but the U.S. Dept of Energy has put up results of airborne radiometric surveys in the vicinity of Fukushima. The data show the main plume on land extending north-west from the plant. It’s instructive to compare the latest survey (from flights on March 24 & 26) with the earlier flying (prior to March 22). The radiation appears to have diminished considerably, which says to me that the bulk of it comprises the short half-life I-131.

Nature out today does the service of converting the earlier map (but note, not the latter updated one) into SI units, for non-American readers, within what is generally a reasonable piece.

MODERATOR
I am not quite sure as to what you are alluding. Refs/Links are actually encouraged by BNC. Too many links in a comment, however, do sometimes mean that the comment may be deemed spam by WordPress. I will pass this on to Barry for comment.”

Yeah, I was posting the first post with links, when it told me something like that. So then I wrote the post without links.

The large jumps 1-3 orders of magnitude UP can be measurement errors, of course, or a secretary wrote something wrong, or whatever. Problem is there shouldn’t be any Te-129 at least not with Bq ratio 13500 to Te-129m in first place, because Te-129 has 69.6 min half-life and his parent Sb-129 4,4 hours and its beta parents some seconds.
see here:http://www-nds.iaea.org/relnsd/vchart/index.html
Anybody?

@Jan
I’m not sure exactly what the data are that you are looking at, but consider this: Te-129m is a direct fission product, and also, I think, that some of the decays of Sb-129 go to Te-129m as well as Te-129. Te-129m has a half-life of 33.6 days and decays to Te-129. So the activity of Te-129 should be the same as the activity of Te-129m at this time.

Is this the correct thread for posting Fukushima Daiichi?
MODERATOR
Right thread for up-dates on the situation at Fukushima. Switch to technical OT if you wish to elaborate at length on the current readings, reactor situation etc.

From the 2001 Sep 11 World Trade Center experience, only aiplane wheels retained enough kenetic energy to pass through the sturctures in recognizable condition. A pothograph sequence of a jet fighter flown into a concrete wall in a test at Sandia resulted in a totally destroyed aircraft and a small chunk of missing wall, maybe 20 cm in diameter and 5 cm deep at the center.

Of course the newer designs which place the reactor underground are superior in that it is essentially impossible to fly an airplane to impact the reactor vessel; see the just previously given link to a small modular reactor survey.

Well, an IEEE Tech Talk note doesn’t make the Lahey perspective correct. But it is clear that he stands behind his interpretation (quoted in The Guardian). Exerpt:

This morning, Lahey elaborated on his analysis for IEEE Spectrum, which he said had been accurately reported by The Guardian, but misinterpreted by some. (A careless read of the article suggests a new melt down at the plant, rather an analysis of what probably occurred early on in the crisis.)

Lahey says his analysis was based on the data sources seen by him and colleagues around the world, but that the information has been inconsistent and changes hourly. “It’s really hard to read the tea leaves,” Lahey says. “They keep blowing around… I may be wrong. I hope I’m wrong.”

However, his best take is that “all cores have melted, and it appears as though Unit 2 has melted through.”

Still missing is Lahey’s specific observations indicate in particular that “Unit 2 has melted through.” The concluding paragraph:

Our correspondent, John Boyd, questioned experts in Japan about Lahey’s claim, but they were doubtful. Hidehiko Nishiyama, the deputy director general of theNuclear Industry and Safety Agency (NISA), did not see evidence of a big breach of the pressure vessel, but acknowledged that its not completely contained. “When we look at the release of radioactive material up to now, while we do not believe there is any major breach either to the pressure vessel or the containment vessel, we are pretty sure there is some leakage,” he told Boyd.

@nkinnear
“Te-129m has a half-life of 33.6 days and decays to Te-129. So the activity of Te-129 should be the same as the activity of Te-129m at this time.”

Yeah, exactly, in a certain ratio.
Yet somehow there are the large even multiple orders of magnitude fluctuations of the Te-129.http://xmarinx.sweb.cz/Te-129_Te-129m.xls
Are this another errors in the TEPCO measurements, or does it signify something?
I don’t know, that’s why I’m asking.

Mentions what’s been a concern all the way along, that fuel may have fallen into configurations that have allowed bursts of criticality. This kind of accident has happened often enough to be fairly well known — it’s a very fast and usually very brief event because it heats up the material and that usually separates the fissionables or boils water that’s moderating neutrons (slowing them down, which makes more fission events happen).

New readers should look at the word “moderation” — slowing down neutrons, “moderating” them, makes fission events increase, not decrease. Water is a moderator; water vapor isn’t, so when a fissionable material that includes water reaches criticality it boils — and its density decreases, the water goes away, the neutrons are no longer moderated, and the criticality stops.

Some criticality accidents have cycled that way — flash to criticality, heat, boil, cool, condense, flash — until enough water boiled away or boron was added or other interventions interrupted the problem.

Ok, I’ve taken a look at the readings you pulled together (thank you!), and honestly don’t see anything that looks like a concern to me. I’d have to do some actual calculations to be sure, but there are a number of factors to consider that are affecting these numbers.

First, recall that Te-129m has ~34 day half life – and it’s primary mode of decay is to drop back to Te-129. (branching factor is about 63%). So as long as we’ve got Te-129, we’ll have Te-129 also. I think this may be the biggest piece that you’re missing.

Next, these are atmospheric readings taken in the open. Not only will we get variation based on wind conditions, precipitation, etc., but also there is almost certainly some variation in how much is being released from the plants.

So the amounts will vary from day to day just because of those factors.

It’s made even more difficult because the data is spotty – we don’t even have every day at each location for both isotopes…

So the portal sample Te-129 increase from the 23rd to the 24th, for example, could easily be because a lot of Te-129m was present shortly before that (e.g., from the 23rd, where we don’t have a reading), or because more radioisotopes of all types happened to be released, or blown, to that location on the 24th than on the 23rd… or a combination of all of these factors.

@Jan
I sure have no idea regarding the many various reports of activity. I can make no sense of them myself. There are so many inconsistancies in the reported isotopes that I have about given up trying to understand them. I was just trying to address your comment about the fact that there should not be any Te-129 present at this time, due to its short half-life.

The relatively recent increase in background radiation due to medical, military, and civilian nuclear industry seems somewhat accompanied by increasing cancer rates as other causes are removed (cigarettes, lifestyle).

A WHO report says:

“… cancer rates are set to increase at an alarming rate globally. We can make a difference by taking action today. We have the opportunity to stem this increase. This report calls on Governments, health practitioners and the general public to take urgent action. Action now can prevent one third of cancers, cure another third, and provide good, palliative care to the remaining third who need it, “said Dr. Paul Kleihues, Director of the International Agency for Research on Cancer (IARC) and co-editor of the World Cancer Report.

see, for example:

http://www.who.int/mediacentre/news/releases/2003/pr27/en/MODERATOR
You are skating on thin ice here Chris. I could delete this post on the basis that you are deliberately distorting the facts and providing links which do not support what you are saying. I am leaving it up un-edited as an example of what occurs. Further violations of the BNC Commenting Rules will result in editing/deleting of your comment.
Everyone, please check the BNC Commenting Rules before submitting your comment or risk having it edited/deleted.
Thank you.

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What of the common misconceptions as to the shield build of the AP100 in regards to it’s impact characterize appears to me to me a misunderstanding of the purpose of a shield building.

There are many ways to protect something from impact hazard. One is to build them with thick concrete walls, another way is to build them with something that will absorb or some combination of the two.

The shield building on the AP100 doesn’t need to survive an aircraft impact.

It needs to absorb enough energy so that the containment building survives whatever remaining impact energy there is.

Chris Warren, be careful not to dissemble. That is why you remain on permanent moderation.

That WHO report webpage you link to has zero mentions of ‘nuclear’ or ‘fallout’ or ‘Chernobyl’ or ‘plutonium’, and one mention of radiation:

(headline) World Cancer Report provides clear evidence that action on smoking, diet and infections can prevent one third of cancers, another third can be cured…

(much deeper down) The report says that the worldwide breast cancer epidemic has many causative factors, including reproductive history, genetics, radiation (especially at times of breast development), and the Western lifestyle with a high caloric diet, obesity and lack of physical activity

That would be mammograms and other medical diagnostics, I suspect. Where is the civilian nuclear industry mentioned? Why did you label your comment “Nuclear toxicity”?

I just wanted to thank you for the posts with links you’ve been posting. That high res video was pretty amazing. Were you able to recognize much beyond the head & crane? Oh, and in one unit I was pretty sure that had to be the empty fuel transfer canal.. It just looked to me as if the roof is covering up almost everything at both units – or at least there is so much rubble I’m assuming that’s what it is….

Then outside one of the buildings there was the large pipe to nowhere, I’ve no idea what that was. I’d think that someone more familiar with actually looking at the refueling floor & with the buildings and layout can probably make more out of it than me by far.

@RD
Yeah, hopefully you’re right. The measurements are really very spotty and we don’t much know how they come to the figures and who worked them to the pdf. It was just striking to me there at one moment was measured 13500 times (the Te129/Te129m Bq ratio should be like 694?) more Bq Te-129 than Te-129m -it was the reading I was so amazed with, that I checked the other records. But maybe it is just an error, it would be not the first one there…

Moving post from Philosophical thread per Moderator request… to fill anyone here in who hasn’t been following that thread, a debate started about the robustness of the AP1000 containment, with accusations about how statements to the contrary were unsubstantiated personal opinion – which led to the start of a discussion about licensing, etc. I’ve added the bolding, and snipped out the center bit to shorten it, leaving scope & results sections. Moved post follows:

Rational Debate, on 31 March 2011 at 9:03 AM said:

To those who don’t already realize it, you can find the AP1000 Final Safety Analysis Report and relevant other documentation about the design online wihtout too much trouble.

This stuff isn’t kept secret. The licensing process is extremely in depth and detailed. There are multiple steps, and every bit of the design and all associated assumptions and calculations, materials, etc., are submitted to the Nuclear Regulatory Commission multiple times during that process. At each step NRC then goes over the information with a fine tooth comb, using experts for each area, system, or accident scenario – plus of course a more integrated ‘big picture’ evaluation by experts also. Just go to NRC.gov and you can read up about just what licensing a design entails, and find many of the AP1000 documents too (or links to where you can find them). Any time the NRC has any problem with any aspect, they demand and get either proof from the designer that the design does meet requirements and exactly how it does so, or the designer revises the design until it does meet requirements.

That’s just for the United States – every nation does their own licensing – so to whatever depth each nation goes in licensing a design, the AP1000 has been scrutinized yet again by an entirely new set of experts. As best I know, most use a similar in depth iterative process to design licensing. So anywhere the AP1000 is licensed, it has satisfied large teams of experts that it meets very stringent requirements for function, safety, and so on.

The design of AP1000 takes into account the potential effects of the impact of a large commercial
aircraft. The impacting aircraft analyzed is based upon the impulse time curve provided by the
NRC in July 2007. The impact of a large commercial aircraft is beyond design basis.

Scope

The evaluation of plant damage caused by the impact of a commercial aircraft is a complex
analysis problem involving phenomena associated with structural impact, shock-induced
vibration, and fire effects. The analysis of the aircraft impact considers structural damage, such as
that caused by the penetration of hardened components (e.g., engine rotors, landing gear).

An assessment of the effects of aircraft fuselage and wing structure is performed.

An assessment of the effects of shock-induced vibration on systems, structures, and components is
performed.

An assessment of the penetration of hardened aircraft components, such as engine rotors and
landing gear is performed.

Perforation of analyzed structural components is not predicted; therefore, realistic assessments of
the damage to internal systems, structures, and components caused by 1) burning aviation fuel and
2) secondary impacts are not required.

{snipped for brevity}

19F.3

Results/Conclusions

The AP1000 Aircraft Impact Assessment is detailed in Technical Report APP-GW-GLR-126
(Reference 1). The assessment concludes that AP1000 can continue to provide adequate
protection of the public health and safety with respect to aircraft impact as defined by the NRC.
The aircraft impact would not inhibit AP1000’s core cooling capability, containment integrity,
spent fuel pool integrity, or adequate spent fuel cooling based on best estimate calculations.

The assessment resulted in the identification of the following design features and functional
capabilities; changes to which are evaluated and reported in accordance with 10 CFR 50.150(d).

19F.3.1

Shield Building

The shield building as described in Section 3H and Figure 3.7.2-12 (Sheets 7, 8, and 9) is a key
design feature for the protection of the safety systems located inside containment from the impact
of a large commercial aircraft. The assessment detailed in Reference 1 concludes that a strike upon
the shield building would not result in the penetration of the containment vessel such as to cause
direct damage or exposure to jet fuel of the systems or equipment within the containment vessel.

The location of key safety-related components inside containment, including the reactor pressure
vessel, steam generators, and reactor coolant loop, was analyzed to show that structural integrity
was maintained as a result of shock-induced vibrations resulting from the impact of a large
commercial aircraft. The assessment detailed in Reference 1 concluded that the loads induced by
the impact of a large commercial aircraft are enveloped in all situations by the forces for the safe
shutdown earthquake.

This is very interesting about the AP1000 and the end with the earthquake is illustrative. I would think any earhquake above say 5.5M is more energy coupled to the containment building than a jetliner impact. Yet all the nuke plants in Japan survived it. Problem at Fukushima was the tsunami, which I think will have way higher impact momentum than a jetliner.

I regard these amounts of iodine, in the context of its production, is properly described as toxicity.

I regard iodine 131 as a toxin.

Whether this leads to morbidity is a separate matter, and whether this then leads to mortality is another separate matter. These two issues will be resolved only after the Fukushima nukes have been stabilised.

The only reason why food and water is being tested is that hot isotopes are inherently toxic.

MODERATOR
A reminder of the topics/subjects you should be posting on this thread:

“Please restrict all discussion here to technical information, analysis, criticisms and questions on FD — no philosophising or excursions into whether nuclear power is ‘good’ or ‘bad’ or the implications of FD for the future of nuclear power (except for new technical developments, e.g. safety standards), etc. You may impart your deep wisdom on how the world should work on the Philosophical Open Thread.”

When a comment is posted on to the wrong thread it causes a cascade of answering comments on the wrong thread – which means that your message will be lost to those reading the Philosophical OT thread.It seems, mainly, to be the technical experts who are wrongly posting on the Philosophical OT.
I am looking in to a way to move these comments to the right thread but in the meantime I will have to start deleting off-topic comments (as per BNC rules)and asking you to re-post.
Please try harder to post your comment on the appropriate thread.

Note to MODERATOR : This is a reply to the discussion that was started in the “philosophical” section.

I said :
“At some point highest Transuranics (Americium, Curium) prevent safe running of the reactor.”

Barry Replied

“That is not correct. The equilibrium concentration of Am and Cm in pyroprocessed metal fuel (after multiple recycles) is in the order of a few percent, with more than sufficient delayed neutrons to keep the reactor stable. This is not theory, it is proven engineering based on extensive fuel testing at Argonne West in the late 1980s.”

My source was the last edition of Stacey’s “Nuclear Reactor Physics” where he says
“Based on the studies to date, it is the preponderance of informed opinion that sub-critical operation will be required in at least some of the reactors in the international “fleet” in order to fully achieve the closed fuel cycle.”
As it is the basic book for a lot of freshly minted nuclear engineers, you may want to discuss that assertion with him.

I just wanted to thank you for the posts with links you’ve been posting.

Thanks for the thanks!

And thanks for the thumbs-up on that video linked by KBMAN. Your review moves that video up our watch-queue. We live on our yacht, currently in Hobart. Australian internet is bandwidth-capped, especially if like us at the RYCT, access is via a WiFi hotspot at the yacht club. We buy the max-monthly allocation – even so we have to carefully ration all content. We put video links in a “queue” so when we stop for a coffee at Zums cafe we can download. Worse, in the last ~10 days Youtube has defeated downloads, so we are reduced to snuggling around the iPad to watch streaming video at Zum.

I hoped that Will David/Atomic Power Review would prove to be a reliable source. I’m not so sure now – I think his “double breaches” speculation has been defeated by emerging facts. I’m referring to his assertion:

TEPCO, NISA and the Japanese Government now clearly (…) also associate the volumetric flow rate of injection water to the reactor cores as being roughly directly transferable to the trenches.

Charles, that does not apply to metal fuel that has been electrorefined — I presume they are talking about experience with oxide fuel. My data is straight from the horses mouth, i.e. the key fuel conditioning facility folks at INL (formerly Argonne West)

The passage I quoted in Professor Stacey’s book comes right after the description of the IFR reactor and pyro process, so I would be surprised that he didn’t take it into account.
A possible explanation of this divergence of opinion could be that thermal fission and/or long delays for reprocessing yield different distributions of minor actinides, that are less favorable in terms of reactivity control than irradiated fuel coming straight from an IFR.
In such case, an IFR “starting from scratch” pure U5 or Pu9 could have an infinite reprocessing ability, but an IFR starting from reprocessed old PWR spent fuel (Including Am, Np and Cm) would be more troublesome.
This is just an hypothesis though. I recon you are closer from the horse’s mouth than I am.

While you are asking references to the “Argonne folks”, can you ask if “IFR in Submarine” is something that has been studied somewhere ? After all, the first submarine reactor in the “USS Seawolf” was Na based, and a submarine containing an automated power plant could be entirely pressurized with Argon (no Pun intended), even in the turbine room.
That could potentially settle all the problems related to tsunami, earthquake, loss of access to coolant or penetrating device (plane or bomb).

Darn it Jan, I don’t know what the deal is with their readings – skimpy as they are. That was a good catch on your part, and sorry to be so slow on it.

As you note, at one point the ratio Te-129/129m is 13529. But it varies all the way down to 0.79. 4 of the ratio’s are in the 1.xx neighborhood.

Of course I’d expect the ratio to change since we’re not creating more 129m directly… but clearly it ought to be a progression in terms of the ratio for any given day. This is all over the map.

I still can’t go for a re-criticality scenario, because other isotopes that would be expected aren’t being reported. Even if a reactor was critical, it looks like it would be producing Te-129m, not 129 – although it also looks as if Sb-129 may come into play depending on release route.

I’ve been trying a little bit to find relatively current BWR source terms online and not having a lot of luck. Did find NRC’s Rascal program which lists source terms but I’m not sure if they’re the most current… They initially set Te-129 = Te-129m (.63)

So darned if I know what the deal is with the TEPCO monitoring analyses, Jan. Plus what I/we really need to do is look at the full set they’re saying they’ve detected and compare it to the source terms for various conditions (e.g., cladding failure v. core melt v. melt thru RPV) and see what appears reasonable. It’s the overall pattern that should tell us far more than looking at individual isotopes. Even so, clearly there are some things that are just off, and don’t seem to make much sense on the face of it.

RPV or containment? they are two different items, obviously. I thought the idea was that the meltdown may have breached the RPV but not the containment… and I believe the containment is actually steel with concrete around it if you believe what you see in the attached photo from a similar reactor in process of construction…

Perhaps this has been mentioned before, but during the “is-there-or-is-there-not-water-in-the-storage-pools” period, did anyone think to overfly the reactors at night and look for the tell-tale glow of Cherenkov radiation?

Would the energies involved in a dry pool be high enough to generate Cherenkov Radiation in air, or would it just happen if there was water?

@Steve Darden: I liek the info on nuclear tourist’s web site, but I am not certain it is completely factually accurate? there are two covers, one for containment and a second for the RPV. it appears the one they are showing as being for the RPV is actually for the containment?

thanks for the pictures. you can clearly see either the containment or RPV lid in the corner of #4 (round yellow thing). can’t really see much else though. it seems that the crane in #1 is clearly off to one side, which is why the roof did not drop all the way down to the refueling floor on the one side. it is clear though that the steam rising from #4 was from the SFP. it is also interesting (as point out in other threads) how it was that the explosion in 4 did so much damage to the entire structure surrounding the containment…

I haven’t been here for awhile and so I am making my way through comments, so I apologise if this has been dealt with. I have mentioned this before, but one of the reasons or maybe the main reason Dai-ni escaped the problems of Dai-ichi is that it never lost outside power. No loss of power, no problem with maintaining cooling. They lost their backup power and/or sea pumps. Three reactors there have been rated as INES 3. Not sure it should be that high, but that may be because of their loss of backup power. This was 2 weeks ago that I last mentioned it. I can go find the links, if anyone is interested. Now a non-problem, but will be important in a full analysis of the situation and how it might have been worse.

One interesting point of speculation on the explosions, perhaps already mentioned, is that the lighter construction over the refueling floor for reactor building #1 may have resulted in less serious damage – because it blew out in a way that limited damage to the rest of the building. Certainly, recalling the video, there was a visible upward pressure pulse from that explosion that, confined by a heavier structure, might have caused something more like reactor building #3’s damage.

They’re having trouble, George, because some of the equipment, pumps, electrical items that have to be checked or repaired are in the turbine building basement or the trenches. So they’ve got to get the highly contaminated water out before they can make much more progress – or figure out and construct a work around if that’s possible.

You’d think we would get a status on the activity of getting the radioactive water out of the cooling buildings…. but I guess they are waiting for (processing???) equip or tankage or both from someone (the French)??

While ion exchange resins are routinely used to reduce the circulating small amounts of fission products and activated reactor materials, this is far from routine levels of radioactive material, plus the cooling water is now salt water, not very pure water, so I don’t think ion exchange resins are going to be useful. An overwhelming amount of ions present mostly from the salt water. Evaporation with filtering then burial, maybe. Not sure how practical that is either. Dilution in the ocean is the most tempting option. Not very politically desirable, but may be the best of the options and is already going on to some extent.

You can find bits of updates if you check the various agencies reporting status. Pain in the rear, I know. But there’s TEPCO, NISA, JAIC for official sources, and then I hit NHK news & world nuclear news too (seems like I’m forgetting one or more).

The rest of this is a bit off the cuff…. Basically tho there are quite a few different drains, sumps, tanks for hold-up (delay & decay) tanks for storage, transfer tanks, etc. Each is associated to varying degrees with various types of waste water at nuclear power sites such as laundry, equipment drains, floor drains (& drains can be from areas where there’s no contamination, or areas where there is, so those are mostly separate) radwaste treatment systems etc.

So it sounds like they’re checking what might be reasonable to use, then how much space is available, and where there’s not enough space, where some can be made by transferring lower activity wastes into other tanks/hold up locations and so on.

Then before doing the transfers, they’ve got to decide how – thru existing lines or if they have to rig something…. and either way, before they can transfer they’ll have to check integrity of connections, piping, etc.

Finally, they have to actually do the transfers, which considering that power is still a problem probably means a good bit of work too, quite possibly including having to set up new transfer lines or connect somehow to a pump that works/has power, like a fire pumper truck.

So something that sounds like it ought to be fairly quick and straightforward probably actually requires a good bit of time and effort.

I wonder how much the tsunami may have been able to back up some of these systems, forcing water in thru the discharge lines or flooding drains from the surface outside the buildings… or flooding from building drains that were support buildings and got washed away by the tsunami. I don’t know all of the systems well enough to know if chances of that were very little, or fairly large. Obviously there would be valves on lines that led into more contaminated streams that would for the most part prevent this, but its the more pedestrian lines and drains – and the temporary storage tanks that might be associated with those that I wonder about. Just can’t help but suspect that with a tsunami, they may find they’ve got sea water places they never expected.

The one backup that survived was the battery backup. What are these things that can take a quake and a tsunami and keep going ? I want some of these for data centers. All i got is a big pile of lead-acid batteries.

Not sure what piece of equipment they used to inject salt water into the reactors (weeks ago). Perhaps it was a fire truck.

At any rate it took someone w/ an in depth knowledge of how this plant works in order to figure out where to actually hook up the hoses. A standard worker bee would only have the training to know what button to push or what back up systems were available but not where to hook up a fire hose.

I believe the battery backup used was NiCad? they looked a lot like NiCad batteries I have seen. did that save the day from the tsunami? I doubt it. I am willing to bet the only reason they survived is because the battery banks were in a room either higher than the height of the tsunami or sealed from the effect of same…

@ Schla, William, anyone else re treating the water – there are quite a few different ways, all depending on just what it is you’re trying to do. Many are used routinely at nuclear power plants.

Nothing is routine about the current situation, of course, especially with the sea water as an added complication. At least, I’m not aware of situations where they’ve needed to treat highly radioactive sea water – tho that doesn’t mean it hasn’t either occurred or been studied, that’s for sure.

Anyhow, centrifuges can be used to pull out solids and particulates (espc. heavy particulates), ion exchange has already been mentioned and there are different types, cation, anion, and mixed beds, evaporative methods, demineralizers, hold-up tanks (e.g., you store it temporarily to allow short lived radionuclides to decay), filtration, gas stripping, electrodialysis, reverse osmosis, and so on.

Various combinations can be used too of course, all as needed or appropriate. It will be very interesting to hear what they wind up using.

Yeh, I kind of liked the idea of using one of the out-of-work oil tankers to capture all the outflow. But I gather they don’t have a deepwater dock there, or one of the navies would have sailed alongside and provided support/power/water long since, and that didn’t happen.

Too bad. A tanker could sail the stuff well out to sea, and even offer accomodations for vacationers. Rename it the _Hormesis_ ….

> tanker
Yeah, I wasn’t thinking of using a tanker to dump, but to hold and clean the water. Filters get disposed of in waste facilities. Once cleaned, if really cleaned, a tanker-load of water could be brought back and used to refill emergency tanks at reactors, or even parked. Double-hull design would be about as safe as anything else available, and hold far more than the barges delivering fresh water:
“The 50-meter-long barges can each store about 1,100 tons of fresh water….” (from the link above)

Of course parking something like this right at the coast would be a mistake if _another_ tsunami happens; offshore a ways would do better.

The one backup that survived was the battery backup. What are these things that can take a quake and a tsunami and keep going ? I want some of these for data centers. All i got is a big pile of lead-acid batteries.

I don’t know either Sidd, but if you find out, I’d be interested in knowing – especially how portable they are or aren’t.

I will say, however, that very often it seems that something commonly used or well known in one industry or discipline is often not known in another where it could be most useful. Things have gotten so specialized and the mass of knowledge so large, that some/a lot gets missed where it could be really useful.

I think you might be following “kbman”. If so, you may have already seen his remarks last night – way at the bottom of the comments on his …Update 3/30… Are you guys on the same page?

Ferenc almost lost me by citing the neutron beam story as his reason for pursuing this. That story has for some time now been recognized as a case of poor translation. There is a very specific meaning to the term “neutron beam” and to make the measurements to establish that one existed would have required an apparatus specifically designed to detect it. What most have come to accept as the likely physical reality of the story is that when they said a neutron beam what they really meant were locations with high neutron counts.

Then when he made calculations of the Chlorine inside unit 1 by saying that they began injecting seawater on the March 23rd, that’s when I stopped reading. They started the seawater injections at unit 1 in the early hours of the incident, the evening of March 12th. Any point he was trying to make with his calculations was invalid at that point.

I’d also love to see a link for the story about melted fuel in the unit 1 reactor building. Melted fuel in the reactor building? I find that very hard to believe. Enough to cause isolated uncontrolled nuclear chain reactions? I find that very, very hard to believe. I say this because it takes a significant amount of fuel to create criticality, especially given that U-235 is generally only on the order of 5% of the uranium present. I don’t question that you’ve read this, I just would like to review the source material.

I believe it is possible that busted fuel has made its way into the relatively pure water of the Balance-of-Plant components – the turbines, condensers, heat exhangers and feedwater system. Once there I believe that there may be the possibility for some local subcritical fission given the absence of neutron absorbers and the presence of the water moderator. I think it stretches the bounds of reason to believe that enough has accumulated in a small region to make local criticality a possibility.

…and even offer accomodations for vacationers. Rename it the _Hormesis_ ….

ROFLMAO!! Add it to the list with the existing ‘health spa’s’ of mines and some hot springs that way! They could even make it a non-profit, with all proceeds going to help Japan humanitarian aid.

On a more serious note, is it decided that they’re going to use barges? I suppose that’s why they’re going for barges, much smaller draft? Or are they just bringing in fresh water at this point?

Speaking of which, I don’t get it – they’re already using fresh water, so where have they been getting it from? It seems a bit hard to believe that bringing it in by barge would be quicker or easier than getting it elsewhere, but perhaps that’s an indication of how badly the local infrastructure is torn up…

…Of course parking something like this right at the coast would be a mistake if _another_ tsunami happens; offshore a ways would do better.

Yeah, I keep getting periodic flashes of little horrible mental heebie-jeebies over the worry that they may get a really huge aftershock still. Every day that goes bay without one makes it less likely but still… supposedly its fairly common to get an aftershock that is one order of magnitude smaller than the original within a few days… which would be an 8.0. Like they REALLY need something that size, along and probably another tsunami to deal with. Talk about a horror nightmare.

Steve, I was trying to go find the post in question so I could be sure I knew what you were referring to, but I’m having trouble finding it. I searched for El or neutron beam on the philosophical discussion page, but didn’t find either. I’m probably messing up somehow, and sorry to ask this, but could you copy the link to the comment, or the comment header with the date?

Also, you had asked me for my opinion on the KBMAN article, and I’d put it off a little wanting to look at a couple of issues more closely and give you a little more detailed review. In general, however, what he’s saying sounds reasonable to me, albeit with perhaps a few relatively minor errors. Keep in mind tho that I’m not a nuke eng. specializing in core design or even a plant systems engineer – so it’s entirely possible that I could miss some factor or another that would totally change the results of a review on KBMAN’s article.

@ Steve Darden – oh, and the ‘pipe to nowhere’ that I’d mentioned on the video? After seeing the high res. photos to compare to, it’s clear that the pipe is to the stack. Also the debris on the hillside that I’d mentioned? Now after seeing those high res. photos also, I’m thinking that may be from the explosion rather than tsunami, but I can’t tell for sure. No question those explosions blew building bits and debris all over the place.

I’ve been having a bit of a read of Physics for Radiation Protection by James E. Martin today. It’s an extremely good health physics reference book, and a good reference book covering the fundamentals of nuclear physics and nuclear engineering, too.

Extremely useful reading material if you’re interested in understanding, interpreting or talking about the situation in a technical, scientifically literate fashion.

Not sure what piece of equipment they used to inject salt water into the reactors (weeks ago). Perhaps it was a fire truck.

Pretty sure it was, but thru different lines into the core (e.g., not the same route in used at all three reactors)

At any rate it took someone w/ an in depth knowledge of how this plant works in order to figure out where to actually hook up the hoses. A standard worker bee would only have the training to know what button to push or what back up systems were available but not where to hook up a fire hose.

Or a combination. You’d probably be surprised at the general level of training and competence that way.

valves to isolate the main steam line and main feedwater line. Perhaps there is some very large “T” fitting at that location where they could tap into the reactor.

What they’ll probably use is whatever line they’re already tapped into. :0) Theoretically speaking, I suspect main steam would be the last place they’d want to go. Too large, too much risk if anything goes wrong, high rad levels, etc. They’d go for systems like Residual Heat Removal (RHR) or Reactor Core Isolation Cooling (RCIC) or the low pressure ECCS lines before trying main steam.

Barry – Re Prof Lahey – I’ve read the Guardian article quoting him. I’ve looked for and not found any direct material from him about a R-2 RPV melthru (partial or otherwise) and any assesment of facts that support that..

Until we can find direct material from Prof Lahey, then I think he may have been mis-quoted or mis-understood.

Groundwater at the crippled Fukushima Daiichi nuclear power plant is highly likely to be contaminated with radioactive materials, even though its operator Tokyo Electric Power Co. is reviewing its analysis released late Thursday due to erroneous calculations, the government’s nuclear safety agency said Friday.

The Nuclear and Industrial Safety Agency said some of the analysis data on the groundwater presented by the utility known as TEPCO cannot be trusted due to the errors, casting doubts on the finding that the concentration of radioactive iodine in the water was 10,000 times the legal limit….

…Earlier in the week, the utility corrected its analysis of radiation levels in water accumulating in the basement of the No. 2 reactor’s turbine building.

The agency said the density readings of radioactive substances in groundwater samples taken on Tuesday and Wednesday from around the No. 1 reactor’s turbine building may be revised downward, as TEPCO’s evaluation programs for materials such as tellurium, molybdenum and zirconium were found to have errors.

@ George – they must have been listening to you – TEPCO’s report today has a few more details on the various work that’s been done going along. Still not a lot, but a little more anyhow. Also, while I’d read several reports that had said they were pumping the high level turbine basement floor puddle to condensate tanks, which is why I’d replied to you that way – but now reports now sure make it sound as if it was to condensers, rather than tank. Sorry about that. You’ll see that if you go take a look at the last TEPCO report today: http://www.tepco.co.jp/en/press/corp-com/release/11040102-e.html

I noted that the temperature sensor in the bottom of the #2 PV died between 8:30 and 15:30 (from the NISA site). That is another indication of potential containment failure of the PV. Strangely, the last reading was 87.7 degrees Celsius. Not really the melting temperature of steel…

Thanks for the very useful links.
I’ve heard at night at NHK that the measurements of Te-129 are some errors. They said that the Tepco will issue the corrections. So apparently I’m not only one who noticed the strange values and ratios.
Funny thing is that in the brand new measurement from the underground water there is again strange Te-129/Te-129 ratio, so I’m not sure if it is also error or what.http://www.tepco.co.jp/cc/press/betu11_j/images/110331t.pdf
and now they’ve even the Tc-99m rising.
(compared to last measurement http://www.tepco.co.jp/cc/press/betu11_j/images/110330n.pdf)
Looks like the plant is now a real laboratory of strange happenings either in measuring or in reality ;)

I think that to asses what is going on from the complex ratios was why I posted the links to the whole datasheets in the post further above. But I think it would be quite a guess job when we even can’t be sure if the measurements are correct at least like right order of magnitude.

I also don’t find it much likely there is a possibility of recriticality, there is not much anything as a signature of criticality I think. I think Sb-129 could be a likely route, but they don’t measure it, so I don’t know. What I would think the various possible strange transmutations could be a result of complex mutual irradiation in the fancy mix in the leaked 20TBq/m3 underground water sediments possibly also with materials not normally present in the fuel or reactor + the fish they apparently pumped into the cores :)) + the tsunami disgorged crabs, shells and seaflowers. But I’m not knowledgeable enough to dig in this, so I leave it for the experts on sea fauna and flora vs melting core products. (sarcasm)

Someone emailed me today with the figures below saying they came from Tepco, but I can’t find any mention of them on Tepco’s website (not in English anyway). The figures show staff numbers at Daiichi and Daini, and the numbers of workers who have been exposed. Can anyone find the original material?

“This morning, Lahey elaborated on his analysis for IEEE Spectrum, which he said had been accurately reported by The Guardian, but misinterpreted by some. (A careless read of the article suggests a new meltdown at the plant, rather an analysis of what probably occurred early on in the crisis.)

Lahey says his analysis was based on the data sources seen by him and colleagues around the world, but that the information has been inconsistent and changes hourly.

However, his best take is that “all cores have melted, and it appears as though Unit 2 has melted through.”

His conclusion about reactor No. 2 comes largely from the amount of radiation in the water found there and the chemical contents of that water.”

===================================

The March 29th Guardian article quoted Lahey as saying: “”The indications we have, from the reactor to radiation readings and the materials they are seeing, suggest that the core has melted through the bottom of the pressure vessel in unit two, and at least some of it is down on the floor of the drywell,” Lahey said. “I hope I am wrong, but that is certainly what the evidence is pointing towards.”

===============================
So Lahey has no more information than what we have and is basing his conclusion of a R2 RPV at least partial meltthru into the drywell only on the high radioactivity of Unit 2 turbine bdlg water.

Many of us, including Barry Brook disagree with his RPV melthru conclusion. I believe that he may be right that there is partial melting of the cores.

To me, the R1 R2 and R3 drywell continuous air monitoring system (D/W CAMS) radioactivity measurements are essentially the same. If there’s corium in R2 D/W, then it’s there in R1 and R3 also. The D/W CAMS measurements can be found at the referenced NISA site.

Also a question. I was informed that everything would be fine because the reactors had been shut down and it was only a matter of days before they were cool and safe. Why are they frantically working on these. US France and Japan. Why a anti-radiation cloth and why resin. I thought that radiation was not that harmful. I am still not understanding.

Steve, I was trying to go find the post in question so I could be sure I knew what you were referring to, but I’m having trouble finding it. I searched for El or neutron beam

My bad, by reference I was trying to refer to posts by both EL and Rational Debate and the re-criticality issue. It would be impossible to search up your specific post from that reference. This is another example where a forum-style area could really enhance BNC (but that of course means effort).

Like many “loss of control” worries that have been raised, re-criticality seems to be receding.

“29th 16:30~18:25 Switched to the temporary motor‐driven
pump injecting fresh water to SFP.
30th 9:25~23:50 Confirmed malfunction of the temporary
motor‐driven pump injecting fresh water to SFP(9:45). Switched to the injection using the fire pump Truck, but suspended as cracks were confirmed in the hose. (12:47, 13:10) Resumed injection of fresh water(19:05)”

It could have stayed a long time without cooling, which may explain the indicator failure.

The NISA site for March 30 gives RPV pressure readings in R2 and R3 from -0.018 to -0.09 MPa g and 0.02 MPa g. The g means gauge readings relative to atmospheric pressure, a zero being ordinary air pressure. A MPa, mega Pascal is 145 psi or 9.86 atmos. Normal pressure readings with these gauges are ~7 MPa g when the reactors are operating and the design amounts of steam is being generated.

So these RPV pressure readings are from -0.18 to -0.89 atmos (below outside air press) and +0.18 atmos.

I believe it is unlikely the containment vessels are under vacuum. It is more likely that all the stress, explosions and cycling these pressure gauges have undergone, that they are no longer accurate. They are inaccurate and all that can be gleaned is that the reactor pressures are near atmospheric.

@ Geroge Bower
It is almost sure the torus is breached looking at the signatures of the water found in the underground trench. Although now they say at NHK they also found the leak from it leading to the sea through a cable tunnel, so if the’ll not seal it the water will end in the pond below the plant, which is not completely separated from the ocean by dam.
for idea: http://tumetuestumefaisdubien.sweb.cz/pond.jpg
The instrumentation which indicates the breach is the pressure meter of the containment which indicates atmospheric pressure.

Question; Is reactor 3 the 800 pound gorilla? I’m reading JAIF and expert reports, namely on the RPV status, radioactive water, and the estimated fuel melt of reactor cores in 1 (70%) and 2 (30%), but there is less reporting on the status of reactor 3. We don’t have the same degree of updates on the core, RPV, or SPF of reactor 3. Mainly we have vague terms like damaged, or stable. Does this concern any of the experts here? Yes or no, please explain why?

“It would be good to know the flow rate of the leak. I suppose they could calculate it knowing the water makeup into the reactor rate minus what is going off in steam.”
There must not be a leak from the reactor. It is from the water signature very possible it is just the radioactive water from the torus, which was created when the reactor was vented. I doesn’t necesarily imply the reactor pressure vessel is breached.inside the containment, because it would need most probably the completely melted without any water in the reactor pressure vessel- which if we can believe the reports is not the case and in such case it would be not the complete LOss of COolant accident. which the BWR Mark I severe accident mitigation strategies assessmenthttp://www.iaea.org/inis/collection/NCLCollectionStore/_Public/24/072/24072657.pdf describes – which would be bad in case also the pressure suppression chamber is breached. Because the containment can’t be flooded to cool the RPV. So hopefully the reports are true and theres not complete core meltdown at No2 and there is the RPV flooded and no large water leaks on its bottom where the control rods canals are.

Looks like from the mornings TEPCO progress report they are going to try to trace back to the source of the leak in R2. Perhaps they can get a handle on the leakage rate and level of radioactivity from R2 today.

Quote from TEPCO:

after checking the condition,
we began to stop water shutoff and are injecting polymer today(April 3rd).
Tonight, they will depart from Tokyo and will start the work with survey
of the site conditions tomorrow morning April 3. There is a connection
point between the tunnel of unit 2 and this shaft. It was assumed that a
puddle of water in the turbine building of unit 2, out flowed through
this connection point and spilled into the sea from the crack of the
shaft. Therefore, we will investigate out flowed route to the shaft and
implement the water analysis by taking samples in the shaft near the
spilling point to the sea. In addition, from April 2nd, we will implement
sampling at 15km offshore Fukushima Daiichi and Fukushima Daini Nuclear
Power Stations and will evaluate these samples comprehensively.

Also, there is a schematic of how they are moving radioactive waste water from tank to tank on the NISA site. However, I don’t have enough knowledge in order to fully understand it.

> radiation rate … in the torus
Uneducated guess, in normal operation without damage to the fuel, it’d be comparable to that in the turbine, about which Wikipedia says:

http://en.wikipedia.org/wiki/Boiling_water_reactor
“… shielding and access control around the steam turbine are required during normal operations due to the radiation levels arising from the steam entering directly from the reactor core. This is a moderately minor concern, as most of the radiation flux is due to Nitrogen-16, which has a half-life measured in seconds, allowing the turbine chamber to be entered into within minutes of shutdown.”

“… He said that because of the earthquake there were many holes on the plant premises, with water collected in them. With their vision hampered by their gasmasks, the workers could not always see where they were walking, and several workers fell into the holes. The situation was such that it took two days to finish work that normally would have taken only three to four hours, he said….”

From an Australian perspective, the stress at Fukushima shows up a dependence on copious supplies of water, which is particularly scarce inland from the Australian coast.
.
We could do a lot better with engineering designs that dumped the waste heat using air or thermal radiation instead of evaporating water.
.
This is not as radical as it may seem at first glance. Once-through gas turbines use air as their working fluid and dump their waste heat directly into the atmosphere. The cycle could be emulated with nuclear replacing the combustion zone.
.
A crucial difference would be that in a failsafe breakdown, an un-manned plant must passively convect decay heat into the immediate air.
.
If that limits the size of the power plant to 50 MW or less, perhaps that is so much the better for a country whose industries are so dispersed.
.
An immediate implication would be that the power plants could go to wherever the industry is, instead of the industries going to the grid.

Martin Burkle asked about radiation levels around a torus during normal plant operations. My understanding is that it would be in the 10 to 50 mRem per hour range with hotspots around 100 to 150 mRem per hour.MODERATOR
Jeff – Please supply refs to support your understanding . This is required by BNC commemts policy. In future, you comment may be deleted if not substantiated.

“The Dai-ni plants do not have the same problem because the AC power was not lost.”
There is still a lesson to be learned. Why was the power not lost?”
1. Why was the switch room not flooded? Maybe the plants are higher or the wave not has high. Maybe the plants are of a newer design and have water tight doors. Maybe something else.
2. Was the local grid supply the same type as Dai-ichi? Maybe the power came from a newer underground power line. Maybe the power poles were of a different design. Maybe something else.
3. Were the emergency generators lost? Are the emergency generators repaired now?
A lesson learned can be because something worked as well as when something does not work.

I see that the 750 MW Kogan Ck Qld air cooled coal fired power station will get an intermittent 44 MW solar boosthttp://www.csenergy.com.au/content-(50)-renewable-energy.htm
On an annual basis it looks like the extra output will be small compared to coal. It is additional to coal, not instead of. It’s less CO2 growth than otherwise, not a reduction from pre-existing levels or negative growth.

If these projects make little or no difference to baseline emissions I wonder if they are essentially a greenwash. A photo-op for politicians. 10% or 20% baseline CO2 cuts would be more impressive.

John Newlands, on 4 April 2011 at 8:40 AM — Assuming a 21% CF for that location, the average boost is 0.21×44 = 9.24 MW, providing a whole 1.23% elimination of otherwise additional CO2 emissions from that site.

A modest energy efficiency program can easily do at least as well; Kansasians eliminated an impressive 5% of demand over the past 20+ months.

Roger – people are fairly scarce inland from the Australian coast too, as I understand it. So on the basis that you want the power where the people are, it doesn’t matter much if the power stations need to be on the coast.

For a distributed population, though, your point about generating power in useful sized modules is good, and one or two of the the B&W mPower 125MW reactors might be great for Darwin, for example.

—————–

On a technical question unrelated to Fukushima – would it be reasonable to compare the total global radiation exposure for medical purposes, for a year, to the total radiation exposure due to Chernobyl? This is not an easy calculation to get a hold of, but I get the impression that the two are not wildly different.

What’s wrong with using US data and experience? Do you doubt the professionalism of the NRC?

Depends on the evidence?

How did the NRC professionals use the experience of the Sep 11 plane impact into the wall of the Pentagon as data and experience, for other strategic reinforced concrete 0.9m concrete shells spanning 40metre voids?

I doubt they did this?

So it would appear that NRC risk analysis for thin concrete shells on modern nuclear plants is likely uninformed by US data and experience.

I also doubt that Westinghouse used the US data and experience in revising its own documents.

What is your issue with the US risk analyses proponents might be “relying on”? Studies estimate a core damage frequency of 2*10^-5, or one in 50,000 reactor years. N.B. that this does not imply significant radiological release or “disaster”.

However the remaining 20% of Australians amount to 4.4 million, hardly negligible. With the city average of about 1 kW per capita, that is already 4.4 GW of demand. Yet rural industries such as mining will consume a lot more than 1 kW per worker. A quite ordinary mine site will consume 10 MW, mainly in the processing of its ore.

The Toshiba 4S can be installed with an output as low as 10 MW, however its Alaskan installation assumes plenty of water to cool the condenser. That size of reactor we need to be cooled by air.

If more power is available, it is an option to the mine owner to increase the value density of the product to reduce transport costs. Gove once sought 1 GW(th) of gas just to produce alumina. With more power, they might electrolyse the alumina and produce the metal on site. As might Weipa , or Pinjarra .

[deleted incorrect assertion]
Using your figure, this means that when there are 10,000 reactors (arguably at 2060) core damage has a frequency of 1 in 5 years.

The LERF (cited previously) – which does imply significant radiological release, is at or below 10^-5 if US standards apply.

This is large radiological release freq. of one every 10 years – after 2060.

[deleted unsustantiated opinion]MODERATOR
Chris – I went back and looked at the comment by Tom Keen in case I had missed any failure to give refs. I really don’t know what you are getting at as the links are in Tom’s comment.

Why are the ridiculous, snide posts of Chris Warren permitted to stand?MODERATOR
Finrod – I can only moderate according to BNC commenting policy. I have edited some of Chris Warren’s comments. Please point out any other comments (or parts thereof) where you see a violation or a technical point which is not substantiated.

I provided a hyperlink to an EPRI white paper which (bottom of page 3) reports the estimated core damage frequency I quoted. References are given at the bottom. I also provided a hyperlink to a paper which indicates that nuclear energy production has a lower death rate per TWh than any other energy source.

The only statement I did not support with a reference was “much greater risks of unmitigated climate change“, which, on a climate change blog, I thought would go without saying.

What is insufficient about this?

However, you did make this assertion without evidence:

Nuclear energy production only APPEARS safer because the risk is distributed on a dramatically different timescale.

I stand by my statement that nuclear energy production is the safest form of current energy production. And it appears to be getting safer (again, see the EPRI paper). And once we move toward some Generation IV technologies, we can all sleep even more soundly.

You never answered my question: What is your issue with using US risk analyses?MODERATOR
Chris Warren’s violations of the comments policy have been edited.

Go to google scholar and search for “nuclear power” and “aircraft”. The risks aren’t that high.

Another EPRI study available here, goes through, in detail, the results of some computer model simulations of a Boeing 767-400 collision. The conclusion?
“The study determined that the structures that house reactor fuel are robust and protect the fuel from impacts of large commercial aircraft.”

So we can only ask the question – can a reinforced concrete shell spanning 40 metres withstand a hammer-blow of 100 mega-newtons.

If I might use a simple analogy.

50 years ago automobile bumpers could withstand a 30 MPH impact with a tree. Allthe energy ended up being transferred to the occupant. The car survived, the occupant didn’t. Today’s bumpers won’t survive a 5 MPH impact with a tree. The survival rate of the occupant is substantially higher as much of the force of the accident is absorbed by the bumper.

The shield building serves the same function for a nuclear reactor that a bumper on an automobile does. The question becomes whether or not a shield building that deforms and suffers damage from a high impact event does a better job of protecting the containment building and more importantly, the core.

Do the detectors used for official readings reported around the 40km area detect alpha particles? If not, does this pose a yet unknown risk for human or food chain contamination – if – these particles are inhaled or ingested? Alpha particles are scattered then land but are easy to disturb, on trees, on cars, doors, or just about any object sitting outside. Even relatively small amount of localized particles if inhaled or ingested is dangerous to human health. Yet they can go undetected by large area detectors. Ive read that most geiger counters don’t detect alpha particles very well, or at all. I’m trying to understand the nature and danger of alpha particles.http://en.wikipedia.org/wiki/Geiger_counterMODERATOR
Your double up post was deleted. Please do not post the same comments on more than one thread.

Alpha particles are emitted by atomic nuclei in the radioactive process known as alpha decay. They consist of two protons and two neutrons bound together by nuclear forces, and are therefore in fact helium nuclei travelling at high velocity. Alpha particles radiated by decaying radioactive atoms will soon attract electrons, becoming neutral helium atoms (all helium gas on earth has been produced by radioactive decay in this manner).

Alpha particles are highly ionising, but cannot penetrate materials very well. They are stopped by a peice of paper, or the surface of skin, and only penetrate a few centimetres through air, after which they have been slowed down to normal velocity for atmospheric gas and are inert helium atoms. Alpha radiation emitted by external sources is therefore quite easy to sheild against. Alpha radiation is much more dangerous if it is emitted internally. The chief hazards associated with alpha emitting materials come from injecting, inhaling or ingesting them.

So it’s not alpha particles themselves we’d be worried about, but particles of alpha-emitting materials.

Alphas can generally only be picked up by a Geiger counter if the detector has a mica window (like mine).

No doubt there are all sorts of detectors on hand to measure the radiation present at Fukushime.

Since Will Davis did not bother to state the precise measurement, I guess we will never know if those readings are any higher than the others.

It is amazing how someone can write an entire page about something with so little specificity. I ignore those blogs myself, but that’s a personal choice. I prefer the data here, which is stated succinctly and in commonly measured units for comparison.

“By Kenji Hall and Julie Makinen, Los Angeles Times
April 5, 2011, 4:39 a.m.
Reporting from Tokyo—
The operator of Japan’s stricken Fukushima nuclear plant said Tuesday that it had found radioactive iodine at 7.5 million times the legal limit in a seawater sample taken near the facility, and government officials imposed a new health limit for radioactivity in fish.
The reading of iodine-131 was recorded Saturday, Tokyo Electric Power Co. said….”

I’d doubt that in this case — it could be there was already leak water under the plant before this event, undetected.

I’d guess the trenches and pits are below the current water table.

After the tsunami, water that soaked into the ground is probably flowing through the ground toward the ocean — and whatever cracks or leaks in the concrete are letting some of the radioactive water mix with the groundwater flowing through.

So I’d guess you can’t assume the outflow is all water that was put onto the plant.

George Bowers on April 5th suggests that the leakage into the sea is from the Unit 2 torus. The torus are below grade. Assuming that the there is leakage from the torus into the reactor building, there would need to be a running pump to lift water out of the basement of the reactor building.

Translation question if I may — I see references to using “liquid glass” to seal the crack leaking water.
Is this “water glass” aka silica gel, that sets up as a solid? That’s my guess.http://www.google.com/search?q=japanese+translation+“water+glass”+”silica+gel”

The New York Times has found a report dated March 26th written by the NRCs team of specialists. The Times article is at http://www.nytimes.com/2011/04/06/world/asia/06nuclear.html?pagewanted=1&ref=todayspaper
Claim #1
NRC experts are really worried about aftershocks now that both the reactor vessel and the containment vessel are half full of water. This might cause a large break in plumbing or the containment vessel.
Claim #2
Reactor #1 is clogged up by the use of sea water. I think they mean that water can no longer flow freely around the rods. Therefore, there is high danger that the fuel is not where it used to be.

Ted, from my understanding, recriticality is not an impossibility, but the evidence Gunderson presents is not compelling. The chlorine-38 was puzzling but I haven’t seen any reason why sodium-24 was not also detected, under the theory that seawater was in a neutron field. The tellerium-129 is simple – it has decayed from Te-129m, a higher-energy but longer-lived version of the same isotope. You can even see it on the next line of the assay. The “neutron beams” are poorly sourced and not well explained by anything.

Basically we are accustomed in the confusion of Fukushima to half-stories that have no immediate explanation. Gunderson seems to be using a selection of those to try to prop up his story of Fukushima as “Chernobyl on steroids”, a wild and irresponsible speculation he was spreading early on.

I don’t know why you are persisting with this line of argument. It is wildly out of perspective with other much more serious and pressing hazards (e.g. climate change) or even attacks on any hazardous chemical plant. Did you go to google scholar and search “nuclear power” and “aircraft”?

“that nuclear energy production is the safest form of current energy production.”

Your insertion of “current” validates my concerns.

How does that validate your concerns? Nuclear power has killed, and does kill, less people per unit of energy produced than any other form of energy production. I substantiated this claim upthread. Do you have evidence to refute this, or not?

Your claim that the study is somehow fallacious is unsubstantiated, again.

Once more, I urge you to put the risks of nuclear energy into the context of climate change, and into context with the many other risks of not replacing fossil fuels. Not to mention the reality of poverty due to much of the world’s population having insufficient access to energy.

Times article on new threats to plant safety at Fukushima, according to confidential NRC report.

The case for nuclear power does not depend on what happens at Fukushima. With that in mind, we should not make overconfident statements about how all will turn out there.

what do others think?

——-

As a journalist, I have a folder with hundreds of over confident assurances and predictions. I think it’s too late to cover up. Going forward, I think experts need to focus on the questions people are asking, and give answers that include the full array of potential risks and outcomes. People want experts to distill information and technical jargon down to language that the average intelligent person can understand. I’m not an engineer, but after reading hundreds of technical reports about nuclear power and about this crisis, I’m finding very little problem understanding technical concepts, if they explained properly. The confusion arises from engineers and experts that try to hide certain aspects, while highlighting aspects that support their beliefs. Eventually, after all is said and done, good journalism will weed out those that gave accurate explanations, from those who gave clouded explanations to support their beliefs. We mainly depend on the experts to explain and distill the facts. All of the facts. All of the risks. Anyone with good reasoning skills can then review the information and make critical observations and reports. We don’t need experts to make our critical observations and reviews for us.

Another interesting thing to notice from this schematic is how deep the water must be in the turbine basement. In order for the water to come out the top of the vertical shaft the turbine basement would have to be around 3/4 full, putting the top of the water in the basement much higher than the Torus. This leads me to think that the majority of the water in the basement is from the spraying of the spent cooling ponds.

I still would like to know how much water is leaking out the seals of the control rods though….and where this contaminated water goes. From what I mentioned above it must not be going into the turbine basement.

Times article on new threats to plant safety at Fukushima, according to confidential NRC report.

I would be alarmed if a safety review failed to identify possible problems. That’s the purpose of safety reviews, identify potential problems so actions can be taken to insure those problems don’t occur.

George, did you see a description or picture somewhere saying that water came out of the top of one of the trenches?

According to the descriptions, the cable trenches carry power down to the seawater pumps at the edge of the ocean. The water was entering one of the trenches through a big crack in its side and then running down to the ocean, from the descriptions I’ve seen.

I think the verticle shaft which is fed from the trench below the turbine basement is where the source of contaminated water was coming from. So it would be turbine room to trench below turbine room to verticle shaft to cable trench then out thru crack (now sealed) to ocean.

The link below should take you to a copy of the NRC report. Of course I cannot be 100% sure it is the original, you can judge the material yourself. It does mention the interesting “fact” that neutron sources were found 1 mile from the reactors and that neutron sources between units 3 and 4 were covered with materials moved by bulldozers. The report speculates that the material came from reactor # 3 spent fuel pools.

Thx Harry,
interesting schematic of how they are injecting the Nitrogen. Looks like normally they inject into the torus but in this case they are injecting into the CV and exiting out the torus.

Questions for anyone on a slightly different subject:

1) Where is all the make up water going?? Is it just coming off in steam??

2) If there is leakage from the RPV from (for example the reactor seals) where does this water end up?? I thought days ago that it was going into the turbine basement but now I am not sure as the turbine room seems to be filled up to a level much higher than the torus.

George Bower, on 7 April 2011 at 7:16 AM — For #1, it seems that all makeup water goes to steam as #1 continues to hold pressure. Alas, not so for #2 & #3 so some of the makeup water for those units may be leaking out.

I think the NRC was saying they didn’t know where the neutron sources were coming from (spent fuel pools of Unit 3 and Unit 4 were their primary suspects).
In the assessment portion of Unit 3 your source says the neutron sources bulldozed between 3 and 4 could be from Unit 4 and in the assessment of Unit 4 it says the sources could be from Unit 3.

Leibstadt is a recent, larger BWR with Mark III containment, so please don’t take this as a severe accident plan for Fukushima R1, R2, R3.

Here is a sample of relevant english-acronym correspondence:

The Emergency Core Cooling System (ECCS) of the Leibstadt plant is composed of seven subsystems: one High Pressure Core Spray (HPCS), one Low Pressure Core Spray (LPCS), three Low Pressure Core Injections and two Special Emergency Heat Removal (SEHR) systems. HPCS is the backup system for the steam driven Reactor Core Isolation Cooling System (RCIC). Once the RPV level cannot be maintained by the high pressure injections systems (feed water, HPCS, RCIC) or a failure of these sytems occurs, the Automatic Depressurization System (ADS) will activate in order to allow low pressure systems (LPCS, LPCI) inject into the RPV. LPCI is one of the Residual Heat Removal (RHR) modes. The other two important RHR modes for accident mitigation are Suppression Pool and Fuel Storage Pool Cooling.

All three Daiichi units are on fresh water “feed and bleed”. Why doesn’t the hot fresh water dissolve the accumulated salt deposits. I.e., the salt that is inhibiting contact between fuel and coolant water flow?

George, I don’t see the leak described or pictured — that’s why I asked if you had a source for what you say is happening other than logic and reasoning.

The latest info describing the crack/leak to the sea — at http://www.iaea.org/press/?p=1972 — says something more complicated than the simple cross-section picture — a leak path was via “… a series of trenches/tunnels used to provide power to the sea water intake pumps and supply of service water to the reactor and turbine buildings….”

Those aren’t shown on the simple diagrams.

That IAEA bulletin suggests some of the flow into the pit is from groundwater, I think — blocked by filling holes near the pit in the ground with “liquid glass” (“water glass” — sodium silicate — which sets up as a gel).

My guess has been there’s lots of water in the ground, under and around the plant, now draining toward the ocean, some of it carrying radiation sources from somewhere. I’d be not surprised if some radiation is found from earlier spills that went unreported, detected by the current attention.

But that’s just my guess. If there’s radioactive material in the groundwater, they’ll find it by drilling more holes further away, eventually.

Mostly speculation, but by someone with some knowlege. Excerpt follows:

“… We have a new, section view of the piping at the Fukushima Daiichi No. 2 plant showing, again, the pipe trench or tunnel and the electrical conduit. This is provided by NISA.

Again, TEPCO isn’t sure of the flowpath of water into the pit. It is starting to seem, from various releases and statements that there might be other ways the water is getting into the ocean. One might guess that if the cracks in the concrete are deep, perhaps water flow has begun to create pockets or spaces and perhaps established other flowpaths to sea. My point in mentioning this is that TEPCO probably also thinks the same thing ….”

The NRC report contents are peppered with industry acronyms, some of which are challenging to outsiders like myself.

This is a feature of their mentality. Economists also invent their own jargon. Post-modernists also construct their derived discourses in much the same way (or is ‘way’ to be understood ie deconstructed as ‘discriminated discretionary direction’?)

The more jargon, acronyms, and inconsistent pet-nouns, – the more dubious is the source.

Now, not even a simple concept as High Level Waste has content.

I have always included spent fuel as high level waste. Not so – apparently.

“According to the utility and the Nuclear and Industrial Safety Agency, the square, concrete-covered pit is situated near an intake used to pump seawater into reactor No. 2.

Although the pit is small, it contains highly contaminated water with a radioactivity exceeding 1,000 millisieverts per hour that is leaking into the ocean from a 20-cm crack, Tepco said.

The pit, which is 1.2 meters x 1.9 meters and 2 meters deep, is usually used to store cables. But it is also connected directly to the reactor building through a cable trench, raising the possibility that the source of the contaminated water is the reactor itself, a NISA official said.

The cable trench is different from the pipe trench at No. 2, where water with the same level of radioactivity was discovered Monday. Although the two trenches are connected, no water has been found in the cable trench because it is at a higher elevation, the official said….”

Chris Warren, technically complex subjects require precision in language. But the ANSTO link you cite gives a plain English explanation of the spent fuel situation that does not support your tendentious reading.

To quote:

Are the spent fuel rods stored at ANSTO high level waste?

International and national standards do not consider spent fuel as waste.

I’m sure you would like to call the fuel plates removed from the reactor “high level waste”, but the fact is that they are valuable articles, and valuable materials can be extracted from them. They are not in any sense “waste”.

The processing of these fuel plates is (unfortunately) done overseas. The ultimate waste stream is categorized as “intermediate level waste”.

This information is in plain English on the page you cite, and on one of its sister FAQ pages:

“High-level radioactive wastes are the highly radioactive materials produced as a byproduct of the reactions that occur inside nuclear reactors. High-level wastes take one of two forms:
Spent (used) reactor fuel when it is accepted for disposal
Waste materials remaining after spent fuel is reprocessed”

It depends what type of spent fuel you are talking about. the OPAL reactor uses about 30 kg of low-enriched uranium (~ 20 % U-235) to produce 20 MW. The spent fuel is not classed as high level waste. This is not based on some arbitrary industry jargon, but simply on how radioactive it is!

I believe the HIFAR reactor (now closed) did produce some high level waste, but was sent to France for reprocessing. It is due to be returned to Australia in 2015 as intermediate level waste.

High-level radioactive waste is uranium fuel that has been used in a nuclear power reactor and is “spent” or is no longer efficient in generating power to the reactor to produce electricity. Spent fuel is thermally hot as well as being highly radioactive, requiring remote handling and shielding.

I assume that OPAL spent fuel plates are “thermally hot as well as being highly radioactive, requiring remote handling and shielding.”

So I think we should include spent fuel as high level waste.

If there is some technical reason, then what is it? So far the ANSTO position only gives them a philosophical comfort of being able to tell the public;

The actual grading of radioactive waste is determined by standards set locally by national nuclear regulators, and is not the same word wide.

For example the US does not recognize a separate category for medium level waste, but the EU, and some other countries do. On the other hand the US has a classification for Transuranic waste (TRUW) which, as defined by U.S. regulations is, without regard to form or origin, waste that is contaminated with alpha-emitting transuranic radionuclides with half-lives greater than 20 years, and concentrations greater than 100 nCi/g (3.7 MBq/kg), excluding that which is defined as High Level Waste.

As well some regulators maintain sub classes (A,B.C etc) within a particular category further confusing the issue.

Thus arguing what and what is not High Level Waste is a sterile exercise, as the definition depends on jurisdiction.

Thanks so much for the NRC report. With that, the BNC, the Areva slides and the ordinary TEPCO/JAIF/IDEA info, the situation inside the R1-3 RPV/PCV and SFP is much clearer. Also info on SFP #4 H2 explosion.

@ George Bower 7:16 AM and David Benson 7:29 AM:

The NRC document indicates that on R1-3, the recirculation pumps (located inside the PCV) likely have had pump seal failures. Pump seal failures can result in RPV liquids leaking thru the damaged pump seals into the PCV D/W and torus, and over time could fill the PCV to the level of the pump seals. Not all the water pumped into the RPV would have to go out as steam, it could leak too. The RPV would still be intact.

Example R-1 & R2: “Recirculation pump seals have likely failed (R-1 GE – Hitachi) (R-2 Industry)” . R-2 & R-3: ” Based on the reports of RPV level at 1/2 core height, the reactor water level is believed to be even with the level of the recirculation pump seals, implying the pump seals have failed.”

If a PCV is damaged (as in R-2?), then leakage of radioactive water from PCV to the secondary containment building etc is possible.

If you are going to fabricate accusations like this you had better get your facts right.

Your citation only validates my concerns, and indicates they at least date from August 1993. The Parl. Research Service document says:

The report of the Research Reactor Review examines, among many other things, the issue of the management of spent fuel rods from the HIFAR reactor, which had been accumulating at Lucas Heights since 1963. The Report says:

…
* ‘The spent fuel rods at Lucas Heights can only sensibly be treated as high level waste The pretence that spent fuel rods constitute an asset must stop’ (p. 216).

If you think HLW is based on “simply on how radioactive it is”. Then provide evidence and technical details, and advice on how relevant this is to past spent fuel and current spent fuel and future spent fuel.MODERATOR
Your tone here is descending into “slanging match” territory. Not allowed on BNC as it tends to snowball and have a deleterious effect on the commentary. Same applies to others in this conversation.

High-level radioactive waste is uranium fuel that has been used in a nuclear power reactor and is “spent” or is no longer efficient in generating power to the reactor to produce electricity. Spent fuel is thermally hot as well as being highly radioactive, requiring remote handling and shielding.

I assume that OPAL spent fuel plates are “thermally hot as well as being highly radioactive, requiring remote handling and shielding.”

[deleted violation of BNC’s citing rule. Please provide a link and re-post]MODERATOR
Sorry – I was deleting as you were typing the link into your comment above. Would you like to re-submit the comments that went with the now posted link?

While changes improved safety at the Fukushima No. 2 nuclear power plant, overconfidence, complacency and high costs stymied such action at the now-crippled Fukushima No. 1 plant, according to people familiar with the situation.

The difference in the safety designs was the main reason why the crisis continues to unfold at the Fukushima No. 1 plant–one of the oldest in Japan–while the No. 2 plant a few kilometers south remains relatively unscathed by the March 11 Great East Japan Earthquake and tsunami.

Officials at another Tokyo Electric Power Co. nuclear plant in Kashiwazaki-Kariwa, Niigata Prefecture, analyzed the differences in safety designs at the two Fukushima plants.

According to their analysis and TEPCO sources, there are clear differences in safety levels between the two plants concerning power source equipment, such as emergency diesel generators and transformers at the reactor cores, and pumps used to bring in seawater to remove residual heat from the cores.

TEPCO documents show that the emergency diesel generators located in the turbine buildings at the Fukushima No. 1 plant were flooded by the tsunami and rendered inoperable, except for the one at the No. 6 reactor. This effectively disabled the cooling mechanisms.

After the No. 1 plant lost its power sources, the reactor cores became much more difficult to control, leading to serious problems, including hydrogen explosions that damaged the housing of the reactors.

Radioactive materials have also been emitted from the damaged reactors.

No such problems have been encountered at the No. 2 plant.

The emergency generators at the No. 2 plant were in buildings housing the reactor cores. Because the reactor buildings are much more airtight, the generators at the No. 2 plant continued to function after the tsunami struck.

Emergency generators are also located within the airtight reactor core buildings at the Kashiwazaki-Kariwa plant, which has similar design features to the Fukushima No. 2 plant.

When asked about the differences in the safety designs between the No. 1 and No. 2 plants, an official at TEPCO headquarters said: “This does not mean we have admitted that a problem exists. We will conduct further detailed studies to identify the problems.”

The No. 1 plant was built in the 1960s and 1970s. Improvement work was conducted in the 1970s and 1980s to strengthen its resistance to earthquakes.

The IAEA defines high level radioactive waste as waste material that generates heat at a rate of greater than 2 kilowatts per cubic metre – bout the same power as an electric kettle. Managing this waste requires special procedures to manage both the heat and the radioactivity. High level waste results from the reprocessing of spent fuel from nuclear power reactors.

The previous HIFAR reactor and the current OPAL reactor, at The Australian Nuclear Science and Technology Organisation’s (ANSTO) facility at Lucas Heights, are research reactors. They do not generate nuclear power and do not produce high level radioactive waste.

The Nuclear Regulatory Commission’s statement regarded unit No. 2, and the agency underscored that its interpretation was speculative and based on high radiation readings that Tokyo Electric had found in the lower part of unit No. 2’s primary containment structure, called the drywell. The statement said that the commission “does not believe that the reactor vessel has given way, and we do believe practically all of the core remains in the vessel.”

and from the article Twittered by Barry:

Martin Virgilio, a top official for the U.S. Nuclear Regulatory Commission, said at a House of Representatives hearing that the NRC did not believe that the core of Fukushima’s reactor No. 2 had melted down.

Earlier, a Democratic lawmaker had said the NRC informed him the core had become so hot it had probably melted through the reactor pressure vessel.

http://goo.gl/IqpV0 2 hours ago
It seems the Democratic lawmaker quoted before was mis-informed.

Sure Chris. I’ll try. You certainly have set a very high bar on the level of clarity needed to get the point across to you, but I will attempt to rise to the challenge.

In your post of 10.23 am, you complained that

ANSTO now say Australia has no high level waste!

What about spent reactor fuel – one may ask?

You received a couple of responses, including one from Hank Roberts at 12.27 pm as follows:

“High level waste
The International Atomic Energy Agency defines high level radioactive waste as waste material that generates heat at rate of greater than 2,000 watts per cubic metre. … Nuclear power reactors generate larger quantities of radioactive waste at higher levels of radioactivity than research reactors. Australia’s reactor does not generate high level radioactive waste.”

So Hank referenced a quote clearly raising the issue of the difference between power reactors and research/isotope production reactors with regard to the category of waste generated by each.

Although this should have made it clear to you that your criticism of ANSTO’s waste stream definitions was on rather shaky ground, you ignored Hank’s qoute and persisted with the following comment at 1.07 pm:

In general, I have understood, strictly that HLW included – spent fuel. I have not encountered this definitional drift. The HLW (Spent fuel) is clearly described in the NRC Backgrounder, here:

High-level radioactive waste is uranium fuel that has been used in a nuclear power reactor and is “spent” or is no longer efficient in generating power to the reactor to produce electricity. Spent fuel is thermally hot as well as being highly radioactive, requiring remote handling and shielding.

I assume that OPAL spent fuel plates are “thermally hot as well as being highly radioactive, requiring remote handling and shielding.”

So I think we should include spent fuel as high level waste.

In light of the above, it seems clear that you completely ignored Hank’s earlier point, hence my comment.

The previous HIFAR reactor and the current OPAL reactor, at The Australian Nuclear Science and Technology Organisation’s (ANSTO) facility at Lucas Heights, are research reactors. They do not generate nuclear power and do not produce high level radioactive waste.

In light of the above, it seems clear that you completely ignored Hank’s earlier point, hence my comment

Certainly not. In fact I said something like Hank’s stuff was the only useful contribution.

Anyone reading through the thread would be absolutely clear that the point of Hank’s I was refering to was the one concerning power reactors. Your attempt to dodge and shift impresses no one. In fact your sophistry is absurdly transparent.

It might be pointless but for an undecided person like me it sure points to nuclear energy possibly not being a clean energy. Am I right in saying that there is a continuous buildup of high level waste that needs controling?

Chris Warren may demand the details be kept private, but his public commentary speaks for itself.

The BNC commenting rule regarding questioning motivations is good. Nevertheless there will sometimes be individuals whose motivations truly are questionable. Thats the problem with rules. No formal system can be complete, and a perversely motivated individual can always find the GÖdelian hole.

Eric Moore, the high level waste issue is greatly overstated, and rarely put in context with the really dangerous waste – CO2 from fossil fuels.

A picture might be helpful. Under the “F.A.Q” tab at the top right of the main page there is a link to a pamphlet. In the pamphlet is a photo of the dry cask storage of all the high level “waste” from 31 years of operation of a nuclear plant. Its not large. France has got about 80% of its electricity for the last thirty years from nuclear power. The waste from that energy production occupies a single (largish) room in Le Hague, where it awaits reprocessing.

If you really wanted to dispose of it, it could certainly be done – say by burying it deep in a subduction zone, or a very stable geological structure. No issue. But it would be a dreadful waste because only about 1% of the energy from the fuel has been extracted. The sensible approach is simply to hold it in storage, and either reprocess it for use in current reactors, or burn it, completely, in fast reactors.

If the waste is used in fast reactors, getting the other 99% of energy out, the waste volume for a given amount of energy is reduced by a factor of about 100. What remains is a small volume of radioactive material with a moderate half life. This will have decayed to a level of radioactivity less than that of the rocks from which it was originally mined in about 300 years. That might sound like a long time, but I’ve been in houses that are older than that.

The high level waste is remarkably small in volume for the extraordinary amount of energy it has produced, and managing, storing, or disposing of the high level waste does not present technical or engineering problems, only problems of perception and politics.

> Leo Hansen, on 7 April 2011 at 1:25 PM said:
>> @Steve Lapp 7 April 6:14 AM
> Thanks so much for the NRC report. With that,
> the BNC, the Areva slides and the ordinary
> TEPCO/JAIF/IDEA info, the situation inside
> the R1-3 RPV/PCV and SFP is much clearer.

Thank you Leo Hansen for a good summary at your post above.

MODERATOR – are you keeping a “library/link/list” of reference material cited? A reader can do a site search for “.pdf” and “.ppt” but it’s not very easy.

Could you collect good cites when you’re passing through deleting bad stuff ‘pour encourager les autres’? Just save a text file of the good citations.

I found a link to a more readable copy of the report discussed above (it’s not upside down like the GoogleDocs pages):

fukushimafaq.wikispaces.com/file/view/rst+assessment+26march11.pdf

While I hate arguments over definitions confused with reality, that’s how the world works.

It likely fits the US “… classification for Transuranic waste (TRUW) which, as defined by U.S. regulations is, without regard to form or origin, waste that is contaminated with alpha-emitting transuranic radionuclides with half-lives greater than 20 years, and concentrations greater than 100 nCi/g (3.7 MBq/kg) …”MODERATOR
Sorry Hank – no time to do as you suggest. As a part-time volunteer it is all I can do to keep up with the moderation. I have another life to live:-)

Thanks for your explanation. Well certainly perception is a problem. Having spent fuel rods on top of the reactors at Fukushima that need to be under control for several years before being safe was an eye opener to me. Maybe it is irrational. We will have to see.

“Evacuation standards being reviewed….
… the amount of exposure is likely to rise in these areas as little progress has been made in cooling the nuclear fuels or containing radiation leaks.
Taking into consideration the fact that the situation may be prolonged, the Nuclear Safety Commission has reviewed its guidelines using a 2007 advisory issued by the International Committee on Radiological Protection. The commission now says an evacuation advisory should be issued to prevent residents from being exposed to a total of 20 millisieverts a year….”

If the whole world used nuclear power for it’s energy needs at US levels, and all the fission products from that were continuously sprayed, fossil fuel style, throughout the surface of the planet, what would the background radiation be?
How does that compare with the radioactivity in the whole planet? Or just the first 3 feet of crust? Or in the the water of the oceans?

More realistically:
What about the fission products from just one power plant like Fukushima? Suppose a very powerful bomb, or a set of carefully placed bombs, were detonated in such a way as to pulverise all it’s radioactive inventory. What would the consequences be?

More realistically:
What if, for some crazy reason, human intervention was deemed impossible for an entire week at a normal operating plant like Fukushima just before the quake?
What could we reasonably expect to hapen with the fuel at the reactors and pools?

I know that all of these scenarios come with a probability attached, probably zero for all of them, but knowing this, would still be very interesting.

I think the probability of a large Tsunami hitting a power station somewhere in the world in the next 100 years is probably quite high. Because it is unthinkable and inconvenient to our dreams it is discounted as unlikely. What I am waiting to see is:

I am waiting to see what the outcome of this disaster is because that is gives me a sense of scale. If we can sustain a few accidents/disasters over a period of time from Tsunamis, large earthquakes, engineering failures and possibly terror attacks and the impact on the world is low then I am going to be happy with the idea of nuclear power.

I would imagine we have to consider that the amount of reactors may grow in density around the world and may increase the possibility of multiple.incidents.

I have a suggestion for a simple calculation that might give us an idea of how much R2’s RPV is leaking.

Calculate how much steam is being generated. For someone w/ a nuclear background, they should be able to make some assumptions on decay rate of power output of the rods. Knowing the BTU/sec that the fuel rods should be putting out one should then be able to calculate the steam generation in lb/hr. This number could then be compared w/ the last reported makeup rate into reactor 2:

8 m3/h to reactor #2, –convert to mass flow

makeup rate – steam= leakage from PRV #2

I’d do it myself but my background is BSME w/ entire career in gas turbines.

Granted a crude calculation but it would give us an idea. My guess is that even assuming some pretty high power output from the rods you will not be able to come out w/ anywhere near 8 M3/h.

that’s ~ 8 MW but I’d expect that TEPCO could calculate that much better than MIT and it may be about 5 MW

The interesting thing is that R2 RPV level is unchanging over days. If you injected too little water, the level would decrease. If you inject too much, the level would go up.

For level to be unchanging, either you are injecting exactly enough (unlikely) or the level istrument is not working, or you are injecting too much and there is a leak at the measured level that keeps level constant.

This last case is what the NRC memo indicates, leak at recirc pump seal at 1/2 core level.

“TEPCO is now admitting something assumed here previously; that is, that the reactor pressure vessels are not fully intact. This could allow the hydrogen that’s generated inside them to escape and build up in the drywells. Further, there seems to be very low pressure in the drywells due to condensation of core cooling water that’s leaking out as steam. This action will tend to draw a vacuum on the drywells, further enticing the hydrogen to exit any small above-water penetrations or openings (or gaps between the pressure vessel lid and vessel itself) and collect in the drywells. Hence the need to inert them with nitrogen.

TEPCO now states that the drywells for No. 1 and No. 2 plants are damaged.. the damage to No. 1 being “relatively light compared to No. 2.” This means that hydrogen that gets out of the reactor vessel due to the slight vacuum, but the atmosphere enters the drywell as well and the mixing of a concentration of greater than about 4% hydrogen (the value for burn or explosion is altered somewhat by the value of moisture content present in the air) could lead to another burn or explosion.

Put together this all sounds like a downturn, but taken each as its own fact none of them is particularly surprising and in fact the action TEPCO is taking, knowing for a fact there is serious core damage, is one of the things you’d expect them to be doing as soon as possible after higher priorities are taken care of. This may have been another good reason why TEPCO has been rushing to get access to all the normally occupied buildings and equipment spaces.”

In the bit I quoted, he explains what he means — let me try to paraphrase (remember I’m just reading what you can read):

Damage to the drywell means it’s not airtight, so low pressure in the drywell (caused by condensing steam) would suck air in from outside, as well as suck hydrogen in from the reactor vessel — an unfortunate mixture.

You’ve no doubt seen the ‘condensing steam’ demonstration — put a little water into a metal can with its screw lid off, put it on a stove til steam is coming out consistently (so the air has been forced out and only water vapor is filling the space); then screw the cap on as you remove it from the heat and wait a few minutes — and the can collapses as the water condenses, lowering the pressure inside.

That’s the mechanism he’s suggesting happening, and he’s suggesting that explains why the hurry to inject nitrogen into that space.

again, look at the illustration. Much of the area sharing walls with the containment vessel, on several floors of the building, is likely dark, maybe has radioactive water or dust in it, probably has debris in it, and carries pipes and wires that penetrate the containment vessel. So — if there’s an air leak letting air get sucked into the containment vessel somewhere — how do they find it? By looking. So they’d have to get into those areas.

Makes sense to me.

The only fact we know is that TEPCO is working to push nitrogen into the space. The rest is that guy’s logic — but it seems he’s thought it through and it makes sense enough to me that I posted it.

Better design does make a difference.
The NEI posted a list of changes that have been made to US reactors of the same original design http://neinuclearnotes.blogspot.com/2011/04/major-modifications-and-upgrades-to-us.html
but we have a real world example of better design.
Reactor 6 is a later and better design than Reactors 1 through 5. The key difference is the air tight building around the emergency generator which saved the generation from destruction. Reactor 5, which is of the old design, lost it’s generator but a line was run from reactor 6 to 5 saving reactor 5 from the fate of rectors 1 to 4. We know the same wave hit reactor 5 and reactor 6, but the extra protection saved reactor 6’s emergency generator.
Japans root problem was not upgrading safety features of the older plants.
Better design was the difference.

Re pulling a slight vacuum in drywells by condensing steam from the RPV: If the RPV generates steam at a rate of 5 MW, then to condense this steam over time would require the drywell and supression chamber to transfer 5 MW heat away to containment building.

I doubt that over time there is this much heat transfer. Heating the water in the supression chamber torus to 100C would have worked in the initial days, but after that, this heat sink is gone.

I’d bet that the drywell/supression chamber is still venting steam and that the pressure is above atmospheric.

The vacuum pressure readings that has people in a snit are probably the result of bad instrumentation. Of the 2 P gages in each R2 and R3, 3 show slight vac and one shows positive pressure.

Seems to me that cooling the reactor pressure vessels below the point they’re full of live steam is a major goal, and one they don’t know when they’ll attain.

They’d apply the precautionary principle — do everything they can to avoid the known problem.

They may not know when they’ve attained condensation — except by finding they no longer need to vent steam out intentionally.

At that point they’d want the nitrogen atmosphere already established — and enough available to blow in quickly to keep the inside pressure above the final pressure they’d expect the containment to end up at when the pressure suddenly drops as the steam condensed.

As I recall — and from those demonstration videos with metal tanks — that happens fast even in a large volume, because the steam keeps the temperature evened out as it cools down toward condensation.
Have they mentioned venting steam recently?

Have you seen any mention of the temperature on the outside of the containment concrete? (I haven’t– curious if you have)

Did you factor in the temperature of the ocean from which they were pumping sea water? I’d guess the fresh water tanks on the barges are at atmospheric temperature (which was around freezing a week ago when it was snowing; maybe colder than the ocean). Did you include those volumes of cold water being pumped in — and leaking out — as part of the heat estimate?

Well, it sure would be interesting to see something more up to date, but I doubt if we will unless whoever leaked that one can do it again. That leaked doc, for those who haven’t clicked through, has this header:
—-
“Official Use Only RST Assessment of Fukushima Daiichi Units, Based on most recent available data and input from INPO, GEH, EPRI, Naval Reactors (with Bettis and KAPL), and DOEINE
2100 hrs 3/2612011 The purpose of this document is to provide the NRC Reactor Safety Team’s assessment and recommendations for the Fukushima-Daiichi reactors to the USNRC team in Japan. Our assessments and recommendations are based on the best available technical information. We acknowledge that the information is subject to change and refinement.”
———-

says this limit is 0.427 MPag or 62 psig. Vacuum design limit is not given, but typically is ½ atmos or 7 psia.

If 8 m3.hr of water is vaporized into steam (5MW decay heat would do this see post above) and vented into the PCV, then cooling thru PCV shell can condense all of this if the cooling is 5 MW. If less than 5 MW, say 2 MW, then 40% of the steam would be condensed and 60% vented. Water level inside the PCV would increase (unless PCV leakage prevents this) and PCV water temp would be ~100C. P~ 1 atmos

My impression is that TEPCO is flying totally blind on this, with no idea of how much water is vaporized inside the RPV or how much is leaked from RPV into the PCV. I doubt that they know how much steam is being vented from the PCV or what the PCV water level is or how much water is leaking from the PCV drywell and torus into some other area

The N2 injection is simply H2 explosion CYA in my opinion.

Re injected water temp, if water is injected at ~0C, water heat capacity is 4.2 kj/kg-C so to heat 8 m3/hr water or 2.2 kg/s to 100C is 2.2×4.2×100 = 924 kj/s or .924 x 10^6 j/s or 0.9 MW. So including this sensible heating term means that vaporizing 8 m3/hr of 0C water takes 5.9 MW not 5 MW used above.

I begin to see why there’s concern about the loads on the already damaged reactors with continuing aftershocks. Just how _many_ large earthquakes were contemplated during the lifetime of the structure, in the design and planning?

For those that might be interested the EPRI “Severe Accident Management Guidance Technical Basis” reports can be downloaded from the below links. These documents are technically complex and loaded with jargon but they are a wealth of knowledge.

The below link goes to a detail “drawing” of the Oyster Creek BWR. Its not a perfect fit for the Fukushima reactors because Oyster Creek is a BWR 2 in a Mark I containment while the Dai-ichi units are a BWR 3 and 4s. However, there are useful insights to the approximate location of equipment and their arrangement.

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Sorry I have to spell it out — I thought it would be interesting that the Union of Concerned Scientists stated that nitrogen injection has never been attempted before (to their knowledge) after a reactor has been running. They state it has only been done before the reactor is started. They imply there is no known case study to judge how this will be done or if it can be done effectively.

I’ve also been thinking about the drywell flooding option. If there was no water left at the bottom of the pressure vessel then the corium could melt through, necessitating mitigation by flooding the drywell. Its basically a hot pan in a second pan of water then, which cools the reactor vessel bottom so that it doesn’t give way. In newer BWRs, such as GE’s ESBWR, there are automatic drywell deluge (flooders) fed by gravity from higher resevoir. These open automatically upon too high drywell temp and/or pressures.

Does anyone know if the drywell bulb bottom is designed to take a full corium release when not deluged, ie dry? The concrete at the bottom between the containment and the reactor vessel bottom appears very thick, so obviously this appears a design feature. But can it take full corium release when fully dry?

I did find a model calculation which examines such a scenario for a BWR with Mark I containment, in a severe accident: short term station blackout with associated failure of all emergency core cooling systems.

The assumption of the model is that the RPV bottom head fails, and the corium begins pouring out onto the dry floor of the containment starting at t ~ 280 minutes after the loss of power and cooling.

It seems that the major concern turned up in the simulation was not melting the the drywell bulb bottom. The (model) temperatures found adjacent to the corium stayed less than the melting temperature of the containment shell.

The problem is that the atmospheric conditions in the hot environment above the molten debris are thought to be sufficient to fail the drywell head seals, and that the sustained temperature over time might lead to creep rupture of the primary containment pressure boundary.

I think you’ve stated correctly the reason why flooding the containment is considered an option, as you say, it’s to cool the bottom of the RPV and prevent it’s failure, with the release of corium onto the floor of the drywell.

I certainly would have thought that the time when that option would have been chosen (in the current case) was much earlier on than now, when it seems that core cooling (even if not by a closed loop) has been re-established, and there has been a lot of time for decay heat to begin to die away.

Best estimate CONTAIN calculations have recently been performed by the BWR Severe Accident Technology (BWRSAT) Program at Oak Ridge National Laboratory to predict the primary containment response during the later phases of an unmitigated low-pressure Short Term Station Blackout at the Peach Bottom Atomic Power Station. Debris pour conditions leaving the failed reactor vessel are taken from the results of best estimate BWRSAR analyses that are based upon an assumed metallic debris melting temperature of 2750°F (1783 K) and an oxide debris melting temperature of 4350°F (2672 K). COINTAIN analyses were performed for the debris/concrete interaction occurring without consideration of the possible existence of an overlying pool of water. Results indicate failure of the drywell head seals due to the extremely hot atmospheric conditions extant in the drywell. The maximum calculated temperature of the debris adjacent to the drywell shell is less than the melting temperature of the shell, yet the sustained temperatures may be sufficient to induce primary containment pressure boundary failure by the mechanism of creep-rupture. It is also predicted that a significant portion of the reactor pedestal wall is ablated during the period of the calculation. Nevertheless, the calculated results are recognized to be influenced by large modeling uncertainties. Several deficiencies in the application of the CORCON module within the CONTAIN code to BWR severe accident sequences are identified and discussed.

In the media, here and there, and all over the place in scare narratives, there has been talk about recriticality incidents and it sounded like something along these lines was possible (but what exactly?) given the pumping of borated water into (what did they pump it into?)

Anyway, my question is, after the fission process has been stopped and the reactor has powered down to 7 %, and sheds decay heat from there, can a melting of the core lead to recriticality. what are the circumstances, probabilities, severity, etc? can recrit occur without the water?

From an opinion piece by Mark Lynas in the LA Times, comes this stark appraisal of what would be needed to replace Japan’s nuclear fleet in terms of land area and staggering costs. These figure seem to back-up what has been posted here on BNC in the TCASE series and stunningly re-but the figures provided by Beyond Zero Emissions as critiqued on BNC.

According to some recent number crunching by the Breakthrough Institute, a centrist environmental think tank, phasing out Japan’s current nuclear generation capacity and replacing it with wind would require a 1.3-billion-acre wind farm, covering more than half the country’s total land mass. Going for solar instead would require a similar land area, and would in economic terms cost the country more than a trillion dollars.

Are there any estimates of level, trend and nature of the aggregate emissions from the site?
Given the estimate of a decade long D&D program,
these emissions look to remain a factor for some time, even if the process runs smoothly.
It would be useful to have some assurance that the more extreme projections of a large swath of cesium contamination are ill founded.

You can Google SARA+recriticality+BWR, or
NRC+recriticality+BWR for more details. SARA was a
European study of recriticality in severe
accidents in BWRs, and there are also NUREGs
dating to the mid-70’s which discussed such
possibilities.

My understanding is as follows, recriticality in a
BWR has been considered possibile under the
following circumstances:

(1) A complete loss of station power occurs,
accompanied by complete loss of emergency core
cooling systems. The control rods are
automatically inserted at the beginning of the
accident, terminating the fission reaction.

(2) No active efforts are made by the operators to
mitigate the accident.

(3) A short time after the loss of power and core
cooling the upper core becomes uncovered.

(3) The control rods melt in a part of the upper
core, probably near to the center and top. This
can happen without a simultaneous melting of the
fuel rods, if the control rods are made of boron
carbide, since it has a lower melting point than
Zircaloy fuel cladding. Control rods are relocated
in this way, out of a part of the upper core,
leaving that area with close to normal reactor
geometry, but no control rods. But there is no
water present, only steam; and therefore there is
still no fission reaction.

(4) Just at this point, and before fuel rods in
the upper core begin to melt and relocate
downwards together with the control rods, the
electrical power is suddenly restored to the
plant.

(5) The partially damaged core is then flooded by
cold fresh water, due to the restarting of the
emergency core cooling pumps. Fresh water is the
moderator in a BWR. So re-critcality can now occur
in that part of the core which has been cleared of
control rods, but still has close to normal
reactor geometry.

(6) The fission reaction restarts in part of the
damaged core (re-criticality).

Since the control rods are now gone, the factors
that will limit the re-initiated fission reaction
are the natural ones that always operate in a LWR:
namely void formation and Doppler broadening.

That is: as the fission reaction speeds up, it
generates more heat. The additional heat boils
water, creating steam bubbles in the liquid
phase. Steam is less dense than liquid water, so
it doesn’t slow neutrons nearly as
efficiently. This void formation in turn slows the
fission reaction down.

Doppler broadening of the neutron spectrum also
occurs due to heat generated by the fission
reaction. Neutrons which hit nuclei in the fuel,
or in the cladding, or that hit oxygen nuclei in
the water scatter elastically if they aren’t
absorbed and don’t cause fission reactions. But
due to heat, the nuclei are also moving
around. Such elastically scattered neutrons gain
or lose a little energy as they scatter, and this
will change the overall energy spectrum of the
neutrons. The neutrons will gain energy on
average, as the scattering material heats up. But
thermal neutron induced fission cross-sections
also drop significantly with increasing neutron
energies, so the rate of the fission reaction is
in turn reduced as temperature increases.

Depending on the rate at which fresh cold water is
pumped into the damaged core region, faster being
worse, and also depending on other details, there
can occur a big pulse of reactor power in the
small fraction of the core that is partially
damaged. Depending on how big a pulse and how that
energy is dissipated, the reactor power can either
oscillate and finally die away, continue
oscillating, or possibly die down to some constant
low fraction of the total reactor power.

This is potentially a big problem, if the
operators don’t do anything at all to try to
mitigate the situation.

But the whole sequence of events can be avoided,
though, if the operators inject borated instead of
fresh water into the damaged core once power comes
back, or as soon as they have the ability to do
so. Borated water acts as a neutron poison (like
the control rods) and will prevent re-criticality.

That was actually done in this accident, as I
understand it. The operators pumped borated
seawater into the RPVs, over the damaged cores.

I imagine that uncertaintly about the extent of
damage to the reactor cores and worry about the
above scenario may have been the main reason for
injecting the borated seawater into the cores.

More complete melting of the reactor cores makes
recriticality very much less likely, because the
fuel then relocates downward in the RPV together
with the melted fuel rods. Moreover, the geometry
of completely melted fuel is extremely
unfavourable for forming a critical configuration
with reespect to thermal neutrons: there is no
room to fit the moderator inside a blob of molten
fuel cladding, control rods, and fuel pellets, and
any water that gets trapped or sits on top would
simply be boiled away by the heat.

A critical configuration with respect to fast
neutrons isn’t a realistic possibility, due to the
low enriched fuel that is used in light water
reactors. Critical masses with fast neutrons are
simply too large (even for the optimal spherical
geometry).

Notice that the above scenario for re-criticality
has to occur pretty early on in the accident. It’s
very hard for me to imagine a scenario in which
re-criticality occurs at late times, or once the
fuel has become significantly damaged.

I suppose conceivably, such a thing might occur,
for a vey small fraction of the core, if enough
shattered or disintegrated fuel pellets somehow
survived melting, and found their way into a pool
of fresh water, say in the suppression pool. But
such a reaction would be limited by the same
mechanisms mentioned above, as well as probably
others, like the ability of such fuel to flow away
from the critical region.

George: I do seem to remember seeing that item about injecting water to containment in some of the earlier JAIF updates, but I wasn’t sure whether injection to containment meant just a slow spray of water into the containment, possibly for cooling purposes, or an actual attempt to flood the containment.

I certainly agree with you that if containment flooding were to be accomplished, then all of the major drainage paths out of the PCV, below the level of the bottom of the RPV would need to be closed off as tightly as possible.

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Question: when does TEPCO run out of qualified workers? I mean workers who have both required skills and useful remaining radiation allowance.

I would like to know how fast the existing TEPCO manpower pool is being depleted (I mean their remaining radiological allowances). A week ago WNN reported that 21 out of 370 workers had reached 100 milliseverts [thanks to Hank Roberts 4/11/11 2:01]:

Question: when does TEPCO run out of qualified workers? I mean workers who have both required skills and useful remaining radiation allowance>

A fair portion of the maintenance and upgrades that are done at NPP’s is performed during refueling outages. Since refueling only occurs every 18 months or so there is an industry pool of ‘temporary help’.

“(3) The control rods melt in a part of the upper
core, probably near to the center and top. This
can happen without a simultaneous melting of the
fuel rods, if the control rods are made of boron
carbide, since it has a lower melting point than
Zircaloy fuel cladding.”

false

The boron carbide has the melting point 2763°C – http://en.wikipedia.org/wiki/Boron_carbide, Zircaloy has melting point much lower – The pure Zirconium itself has 1855°C melting point – http://en.wikipedia.org/wiki/Zirconium, (and is alloyed by Sn – melting point 231°C – and or Niobium – melting point 2477°C – to form Zircaloys) and the Zirconium even at much lower temperatures already violently reacts with any water present. So the described mechanism of the recriticality is a patent nonsense and I don’t wonder that it is again not sourced by any link whatsoever – as was several times called for by the moderater here…

Personally I think the recriticality claims about the Fukushima are red herrings (I was looking into it after there were the weird Te-129 readings which subsequently showed being errors) because even if the whole cores would melt through the cladding and end on the bottom of the RPV’s there’s not the unpoisoned (borated etc.) moderator (crucial, without it the chain reaction is impossible in the low enriched fuel) for it to regain criticality) The same for the spent fuel pools, moreover there are the fuel rods packed in the boron carbide racks.

But, not being an expert, I’ve summarized it wrongly. The melting
of the B4C is said to occur at 1500K, due to a reaction of the
carbide with stainless steel. Possibly stainless steel may be in
proximity with control rods in these reactors.

So the described mechanism of the recriticality is a patent
nonsense and I don’t wonder that it is again not sourced by any
link whatsoever – as was several times called for by the
moderater here…

There are many sources describing the scenario for
recriticality. Here’s a link to the SARA study:

Recriticality has been studied for a total loss of
electric power accident scenario. In a BWR, the B4C control rods
would melt at about 1500K (due to a eutectic reaction between B4C
and stainlesss steel) and relocate from the core before the fuel
would during core uncovery and heat-up. If electrical power
returns during this time-window, the duration of which is
predicted to be in the range of a few minutes to about 40
nminutes, it is likely that the core will be reflooded using
water from Emergency Core Cooling Systems (ECCS) or feed water
supplies. Since this water is normally unborated, recriticality
is possible …

Personally I think the recriticality claims about the
Fukushima are red herrings (I was looking into it after there
were the weird Te-129 readings which subsequently showed being
errors) because even if the whole cores would melt through the
cladding and end on the bottom of the RPV’s there’s not the
unpoisoned (borated etc.) moderator (crucial, without it the
chain reaction is impossible in the low enriched fuel) for it to
regain criticality) The same for the spent fuel pools, moreover
there are the fuel rods packed in the boron carbide
racks.

I agree with you about all of the late recriticality claims, and
I would add that the early recriticality possibility seems to
require a perfect storm. But it has, at least, been considered a
possibility.

The Board believed that doubts still remained as to whether the TMI-2 core became critical, or was very close to critical, during the TMI-2 accident and recommended that the NRC establish guidelines that deal with criticality following a severe reactor accident.1362 These guidelines should take into account abnormal geometries and possible core conditions that could result from the accident. The Board believed that the accident scenario developed by the TMI-2 licensee was sufficiently detailed that a series of geometric configurations could be simulated for criticality calculations. Variables that could be estimated reasonably well included the presence of water, oxidation of cladding, melting and movement of fuel, melting of poison rods, and movement of poison.

CONCLUSION

The safety concern was addressed by DSR/RES in SARP Task 4.3: Investigate the Possibility and Consequences of Recriticality in Degraded BWR Cores.1382 The staff’s study was documented in NUREG/CR-56531379 in which it was concluded that there was the potential for recriticality in BWRs, if core reflood occurs after control blade melting has begun but prior to significant fuel rod melting. However, a recriticality event would most likely not generate a pressure pulse significant enough to fail the vessel. Two strategies were identified that would aid in regaining control of the reactor and terminate the recriticality event before containment failure pressures are reached: (1) initiation of boron injection at or before the time of core reflood, if the potential for control blade melting exists; and (2) initiation of RHR suppression pool cooling to remove the heat load generated by the recriticality event and extend the time available for boration.

The issue was not considered to be a major concern for PWRs because of their design that includes a safety injection system for supplying borated water to the core. Furthermore, it was concluded in NUREG/CR-58561417 that, during a severe accident, an unmoderated recriticality of the molten, consolidated portion of a degrading core cannot occur at U235 enrichments characteristic of a PWR. Based on the staff’s efforts in addressing the safety concerns in the SARP, this issue was DROPPED from further pursuit as a new and separate issue. In an RES evaluation,1564 it was concluded that consideration of a 20-year license renewal period did not change the priority of the issue.

“Sorry I have to spell it out — I thought it would be interesting that the Union of Concerned Scientists stated that nitrogen injection has never been attempted before (to their knowledge) after a reactor has been running.”

Nitrogen in the containment is quite standard feature of the newer BWR designs by default to prevent hydrogen combustion in case of a LOCA accident and yes it must be sometimes injected in the CPV during operation to maintain the pressure.

I’m not much convinced about the mechanism of the recriticality you describe anyway:
The B4C-steel eutectic melting would be impossible in cases the RPV would be completely dry, because the Zircaloy rapid oxidation would be impossible in such a case. If it would still not be completely dry as is most likely and Zircaloy starts to burn with steam then even if triggering the control rod eutectic it would have much higher temperature – partly because the exothermic violent reaction with the steam, partly because of the decay heat of the fuel inside, so it would most probably be the fuel rods not the control rods which will loose integrity first.
I think the theorizing about this scenatio is based on tests like this:http://cat.inist.fr/?aModele=afficheN&cpsidt=15755028
But they have major flaw – no fuel with very high after scram decay heat is involved inside the Zircaloy tubes.

Btw. Only a crazy would flood the RPV with even partially melted core with a fresh unborated water. It would be better to leave the RPV dry and flood the CPV instead – as the document you link suggests.

I would be interested in a technical discussion on environmental aspects of Fukushima. Has anyone compiled available data into coherent picture? Particularly interested in total Cs deposition as this will be the important one going forward. Sea water more difficult but should be less of an issue due to high salts which should inhibit significant uptake in marine organisms. Fukushima prefecture is starting to look ugly. Depends whether highs are coherent or spot samples. Anyone?

Although it’s helpful in some ways, I find it a little irritating that they have only given a map of the estimated one-year dose, they have saturated their colour scale rather early at 20mSv, and they have included doses in the month just gone, likely more than half the dose. Is anyone aware of an accessible (less processed) version of current dose rates?

“Under its strategic plan unveiled Sunday, Tepco is planning to fill the containment vessels of the plant’s No. 1 and No. 3 reactor units with water and employ heat-exchanging systems that could include an air-cooling solution. Similar plans are in place for the heavily damaged No. 2 reactor unit but must await the repair of leaks that are allowing the escape of highly radioactive water contaminated by the damaged fuel rods.”

As read from the quote above, Tepco is planning to fill the “containment” vessels.

This must be an error. I think they are just going to cool the water in the PRV by creating a new closed loop cooling system for the RPV and cooling this loop via an air cooled heat exchanger similer to french design. I would assume also that the air cooling would consist of an evap cooling tower.

I don’t detect a mention of filling the containment vessels with water. Mention is made of increasing the level of water to cover the “active fuel”.

1 Maintain Stable Cooling
– Nitrogen gas injection
– Flooding up to top of active fuel
– Examination and implementation of
heat exchange function.2 (Unit 2) Cool the reactor while controlling
the increase of accumulated water until the PCV
is sealed.

Sounds more like they want to increase the water levels in the RPVs and for unit 2 to control the additional release of water until they can fix the hole in the suppression pool …

Current Status [1] (Units 1 to 3) Cooling Achieved by water injection while there is partial damage to fuel pellets.

-Continued injection of fresh water and further cooling measures are required.

Countermeasure [1]: Injecting fresh water into the
RPV by pumps.
Risk[1]: Possibility of hydrogen explosion due to condensation of steam in the PCV when cooled, leading to increased hydrogen concentration.

Perhaps they are anticipating a situation where they can not stop the leakage from the PRV in R2. I don’t know how they would repair leaking control rod seals. Pump seals could more easily be fixed. At any rate it is something “under consideration”. I would think that R1 and R2 would be cooled without flooding the CV’s. Set up a new closed loop on the PRV cooling water using an “air cooled” heat exchanger and that this air cooled heat exchanger would use air cooled water towers.

I would think that R1 and R3 would be cooled without flooding the CV’s. Set up a new closed loop on the PRV cooling water using an “air cooled” heat exchanger and that this air cooled heat exchanger would use air cooled water towers.

It would seem crazy to flood the PCV of R2 if there is a leak in the torus which is what I though they suspected … that would only make the leak worse.

So maybe they’re thinking about that only for R1 and R3?

For R2, it would seem they’ld have to fix the hole first. And that fix will have to be able to take the hydrostatic pressure, before they could flood it.
I also don’t see how they could accomplish that fix with very high radiation levels that may exist near the leak.

It would seem to me to be better to cut the flow rate to the RPV in R2 to the minimum necessary to continue cooling so as to limit the leakage, and like you say, try to set up some kind of air cooling with a closed loop, putting the heat exchanger in a lower radiation area.

George, yes, that’s a very good point about
the additional stress on the PCV and the
chance of another earthquake.

I did see the Areva presentation, and it
certainly suggested that flooding of R1 PCV had
been done. There were also hints that R1 had
had a LOCA caused by the earthquake before the
tsunami hit — it was in a video presentation by a Hitachi engineer. I’ll try to find a link.

I understand why they would want to flood the containment in such a case, but I imagined it
would only be up to the level of the PRV bottom
to try to prevent melting through.

About the JAIF updates: I’ve never been quite clear
what they mean by “water injection to containment.”

Is there a separate water spray system inside the drywell, to be used for cooling to condense steam? Or do they really mean filling the whole thing up?

Thx Cyril for the link, an excellent presentation. I found the reactor core isolation pump/cooling slide especially interesting. The reactor was able to run it’s cooling loop pump off the turbine that used reactor steam as an energy source. No outside source required for the pump, just battery power….pretty ingenious.

Thanks GRLC. Only Iitate is above 2microsieverts/hr of those monitoring stations, and a rough calculation shows that the dose from 15-19 Mar at that location is equivalent to a year at the current dose rate (which will drop further). So for evacuation-lifting purposes, almost all areas should be re-opened unless there is a realistic threat of further releases from Fukushima Daiichi on the same scale as mid March. Certainly people should be allowed back to check on their houses and possessions, where the roads etc. permit.

TEPCO’s briefing slides (4) are available here. My speculation that they would flood the PCV appears to be correct:

Countermeasure [9]: Flood the PCV up to the top of active fuel.

I agree with David – if they achieve their objectives in 9 months I will be impressed and relieved. My understanding is that TEPCO knows little about the actual state of the machinery inside the buildings. And they have no experience of doing such construction in a hot environment – with or without robots.

The TEPCO plan describes the strategy for R1 and R3 fairly clearly: first fix the leaks, seal the containment, then flood to at least the top of the fuel and recirculate and cool as you outlined. For R2 the torus leaks must first be repaired (the “sticky cement” plan?). The annotated TEPCO diagram was excellent.

I’ve found two well-informed sources of analysis on the Daiichi stabilization plan. KBMAN worked 25 years ago on the same generation BWR/Type I containment. His latest on the TEPCO plan includes this

One of the primary steps mentioned in their plan is to flood the containment vessels of units 1 and 3 up to the level of the fuel to guarantee the fuel remains covered and to assist in cooling. They are also looking at building external heat exchangers to be used in conjunction with filtration systems to be able to recycle the water being pumped through the reactors and also cool the water in the containments. This step also helps to provide more effective cooling for the fuel sediment on the bottom of the reactors by conducting heat away from the bottom of the reactor vessel.

They also wish to do this for unit 2 but must first repair the damage to the containment vessel. There is mention of using “sticky cement” to make this repair, I’m not sure exactly what they mean by that. This is presumably the leak caused by the explosion in or near the torus during the first week of the emergency. Meanwhile, the leaks in the containment at unit 2 appear to be flowing directly to the service trench in the turbine building. They pumped thousands of gallons only to have the level rise back up again. They may end up needing to seal up the secondary leaks and treat the entire system – trench and all – as the “reactor vessel”. Stop adding new water and instead process the water from the trench and inject it back into the reactor.

Will Davis offers very timely analysis. His first on the TEPCO announced plan discussed the PCV flooding strategy.

The detailed releases by TEPCO do also indicate the desire to flood the PCV’s or Primary Containment Vessels (dry wells) up to the top of the active fuel region. The few illustrations released so far are not of what you might call a highly technical nature but they seem to indicate at least feed to the plant through the normal feed line and then removal of the water from the suppression pool. There is also one that shows a totally separate closed circuit cooling system that circulates only through the pressure vessel and a heat exchanger. Clearly the plans are in a state of flux and we’ll have to see how this shakes out. To help you understand why some of these considerations are of interest to us, look at the following illustration of an earlier style BWR reactor pressure vessel and internals. You’ve seen this before on this site, but it’s been marked up for this article…

Thanks for your rough calculations and observation that “almost all areas should be re-opened unless there is a realistic threat of further releases”.

The latest DOE dose-map slide I’ve seen was headed First-Year…commencing March 16. So that’s good, it does not sum up the earlier exposures. But as I read the map everything hotter than the blue will continue to be an exclusion zone.

Steve, I haven’t seen the future plans of the definition of the evacuation zone anywhere. I doubt they exist in any formal sense. For reference, the actual current evacuation zone is the inner circle on that presentation.

But I don’t understand your “that’s good” remark – the significant impact on these areas was from 15 March onward, so practically all the initial higher-level dose rates are included in the calculation for that map. I’d like to see a map that starts its year from now, or at least from the start of April. It would look very different.

The continuation of an exclusion zone when access would not be harmful is a repeat of the mass psychology mistakes identified after Chernobyl. This land is not blighted or uninhabitable and should not be treated as such.

But I don’t understand your “that’s good” remark – the significant impact on these areas was from 15 March onward, so practically all the initial higher-level dose rates are included in the calculation for that map. I’d like to see a map that starts its year from now, or at least from the start of April. It would look very different.

My bad – I wanted DOE to be doing what you said. That “must be” why I saw March 16 and thought April 16. There are alternative age-related hypotheses for synapse meltdowns like that…

The continuation of an exclusion zone when access would not be harmful is a repeat of the mass psychology mistakes identified after Chernobyl. This land is not blighted or uninhabitable and should not be treated as such.

I agree. I’ve not done my homework to verify what the projected dose would be. My guess is the authorities will continue the currently defined zone until they are confident there will not be any more “excitement” with new releases from NPP1. I.e., they are excluding in fear of new releases rather than based on existing contamination.

The authorities have been proven right to undertake precautionary evacuations, so I certainly would not rule that out as a rationale.

But absent the precautionary aspect, I would personally say that (at the level of detail available to me) the entire area can be reoccupied now – the highest dose rate in Iitate is barely three times standard background, which is nothing, health-wise. I would expect to improve the resolution of the radiological information, check for agriculture effects and perhaps consider certain limitations on activities likely to stir up dust. Unfortunately this would mean that rebuilding the tsunami-shattered coastal communities will be quite hard. Actually though the coastal strip is one of the less contaminated regions, so perhaps my suggested injunction on dust should be restricted to the NW-running plume of higher fallout.

It appears that all the blue and green areas can be immediately reinhabited, with the yellow and orange areas requiring more detailed investigation. Possibly cleaning up local hot spots; the activity measurements on the ground vary wildly, some measurements have revealed megabecquerel sq m. cesium contamination:

Have you a view as to how much of the 20km exclusion zone could safely be reoccupied (baring future increased released)?

Personally I wouldn’t have a problem visiting anywhere except portions of the Fukushima Plant Site. Radiation levels at the Fukushima plant site are currently running from 9 uSv/hr at Monitoring Post 1 to 500 uSv/hr South of the main building.

Having said that, if I look at a terrain map it’s fairly mountainous. The rainy season is in June in Japan, so some places may end up being more radioactive by the end of June then they are now do to runoff.

So if I put my ‘prudent’ hat on I probably will wait until after the rainy season then look at collapsing the evacuation zone. The iodine will be gone and the cesium will either have run off or attached to the soil.

Steve,
Thx for the updates on flooding the CV. I would think you might need two closed loops one for the PRV and one for the CV water. However maybe there is enough natural heat transfer into the steel/concrete containment structure so a separate loop wont be needed.

As to this “air cooled” heat exchanger. I would think it would be an air cooled water tower. What do you think??

Here are some ground measurements from MEXT:http://www.mext.go.jp/english/radioactivity_level/detail/1304099.htm
I would think there are still some “hot” places even outside the evacuation zone with over 10 mikrosieverts/h of just external dose, so I would think it would first need the real on the ground measurements inside the evacuation zone to assess where it is already habitable -for -I would recommend gradual and on real measurements based – lifting of the exclusion zone.
I think the people should be let back as soon as possible to avoid the effects of protracted stress, which could have in summe more adverse effects than the radiation itself – after the plant is safely stabilized – which I think can fully be achieved after the short-halflives and mainly the radioactive water are gone, especially I-131, Te-132, Te-129m, Rh-103 as much as possible (>8 halflifes) to make the work there easier.

I think the rain season in mid June-July will help very much, because the most affected areas (acording to NNSA measurements) are relatively very close to the shore and as I checked in GE the terrain is quite a slopy in most of the parts and not much people in fact inhabite the mountain area and the Iitate willage is there one of the biggest places. So I think the rains will take bulk of the remaining medium halflifes like Cs-137 with, maybe creating secondary hotspots, but I would not think it will be too extensive in such a terrain. The hotspots created by secondary accumulation is also much easier to burry, because of much more localized.
For idea what did just a short rain with the values -here is fresh example from Oarai:http://www.jaea.go.jp/04/o-arai/Oantai_e/html/graph168.html
To me seems quite clear that vast majority of the exclusion zone will be without much risk habitable after the rain season.
So quite clearly Fukushima consequences will be most probably nothing even close to the Chernobyl -as some “scientists”, even from UN organizations are trying to make the world buy into.

CyrilR quote:
,
“If they just want to get the temperatures down to cold shutdown levels or lower, maybe to 50 degrees Celcius or so, air cooling is great. It could just be radiators like the ones in your car.”

The only problem is they are very expensive. Believe me, I worked for Garrett (now Honeywell). A cheap water cooling tower would be a better solution. (just speculating of course)

Who has access to an accurate, maybe ORIGEN2-derived, tabulation of the decay heat in the Fukushima reactors? (Not a chart, please, and certainly not a chart with the heat shown logarithmically. People don’t know how to read that format. It hides the snuggling-up of the trace to zero, and nuclear savants who don’t get this do their cause harm.)

I’ve developed a hypothesis that a steam geyser is what destroyed building 4. If there was mechanical damage or blockage in the pool, water above 100 C could have accumulated (under 2 atm abs of pressure), then erupted all at once… with energy of up to 24 kg TNT per cubic meter (but no shock wave).

Chris – but water’s heat of vaporization is so large that you dont really get much steam produced… for back of envelope calculations i use 1000 btu/lb to boil water, so even if there were say twenty degree temperature above normal boiling — for every cubic yard, 1/50th of that cubic yard flashing to steam will cool the other 49/50ths of that yard back down to 212…..

unit 4, being in refueling, probably had its pool filled to a higher level than normal operation like units 1-3.

Also it had more elements stored in it, 1331 if i recall vs like 500 for others.

Ground acceleration was reported 1/2G. That amounts to an extra 1 million pounds on the floor just to accelerate the fuel, plus half of whatever the water weighed. If a pool were going to be hurt by the earthquake i’d expect the heaviest loaded one to fail first.

I’m sticking with pool cracked by earthquake, and the violent zirconium-water fire hurt the fuel.
look up zirconium’s MSDS – the powder burns better underwater than it does in air and releases about 2500 BTU/pound.